.\" Copyright (c) 2001, 2002 Steven Knight .\" .\" Permission is hereby granted, free of charge, to any person obtaining .\" a copy of this software and associated documentation files (the .\" "Software"), to deal in the Software without restriction, including .\" without limitation the rights to use, copy, modify, merge, publish, .\" distribute, sublicense, and/or sell copies of the Software, and to .\" permit persons to whom the Software is furnished to do so, subject to .\" the following conditions: .\" .\" The above copyright notice and this permission notice shall be included .\" in all copies or substantial portions of the Software. .\" .\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY .\" KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE .\" WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND .\" NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE .\" LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION .\" OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION .\" WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. .\" .\" __FILE__ __REVISION__ __DATE__ __DEVELOPER__ .\" .\" ES - Example Start - indents and turns off line fill .de ES .RS .nf .. .\" EE - Example End - ends indent and turns line fill back on .de EE .RE .fi .. .TH SCONS 1 "November 2002" .SH NAME scons \- a software construction tool .SH SYNOPSIS .B scons [ .IR options ... ] [ .IR name = val ... ] [ .IR targets ... ] .SH DESCRIPTION The .B scons utility builds software (or other files) by determining which component pieces must be rebuilt and executing the necessary commands to rebuild them. By default, .B scons searches for a file named .IR SConstruct , .IR Sconstruct , or .I sconstruct (in that order) in the current directory and reads its configuration from the first file found. An alternate file name may be specified via the .B -f option. If the specified file is not in the local directory, .B scons will internally change its working directory (chdir) to the directory containing the file. The configuration files (generically referred to as .I SConscript files) specify the target files to be built, and (optionally) the rules to build those targets. Reasonable default rules exist for building common software components (executable programs, object files, libraries), so that for most software projects, only the target and input files need be specified. .B scons reads and executes the SConscript files as Python scripts, so you may use normal Python scripting capabilities (such as flow control, data manipulation, and imported Python libraries) to handle complicated build situations. .BR scons , however, reads all of the SConscript files .I before it begins building any targets. To make this obvious, .B scons prints the following messages about what it is doing: .ES $ scons foo.out scons: Reading SConscript files ... scons: done reading SConscript files. scons: Building targets ... cp foo.in foo.out scons: done building targets. $ .EE These status messages may be suppressed using the .B -Q option. .B scons can scan known input files automatically for dependency information (for example, #include statements in C or C++ files) and will rebuild dependent files appropriately whenever any "included" input file changes. .B scons supports the ability to define new scanners for unknown input file types. .B scons is normally executed in a top-level directory containing a .I SConstruct file, specifying the target or targets to be built as command-line arguments. The command .ES scons . .EE will build all target files in or below the current directory .RI ( . ")." .ES scons / .EE will build all target files in or below the root directory (i.e., all files). Specific targets may be supplied: .ES scons foo bar .EE Targets may be omitted from the command line, in which case the targets specified in the SConscript file(s) as .B Default targets will be built: .ES scons .EE Specifying "cleanup" targets in SConscript files is not necessary. The .B -c flag removes all files necessary to build the specified target: .ES scons -c . .EE to remove all target files, or: .ES scons -c build export .EE to remove target files under build and export. A subset of a hierarchical tree may be built by remaining at the top-level directory (where the .I SConstruct file lives) and specifying the subdirectory as the target to be built: .ES scons src/subdir .EE or by changing directory and invoking scons with the .B -u option, which traverses up the directory hierarchy until it finds the .I SConstruct file, and then builds targets relatively to the current subdirectory: .ES cd src/subdir scons -u . .EE .B scons supports building multiple targets in parallel via a .B -j option that takes, as its argument, the number of simultaneous tasks that may be spawned: .ES scons -j 4 .EE builds four targets in parallel, for example. Values of variables to be passed to the SConscript file(s) may be specified on the command line: .ES scons debug=1 . .EE These variables are available in SConscript files through the ARGUMENTS dictionary, and can be used in the SConscript file(s) to modify the build in any way: .ES if ARGUMENTS.get('debug', 0): env = Environment(CCFLAGS = '-g') else: env = Environment() .EE .\" .B scons .\" can maintain a cache of target (derived) files that can .\" be shared between multiple builds. When caching is enabled in a .\" SConscript file, any target files built by .\" .B scons .\" will be copied .\" to the cache. If an up-to-date target file is found in the cache, it .\" will be retrieved from the cache instead of being rebuilt locally. .\" Caching behavior may be disabled and controlled in other ways by the .\" .BR --cache-force , .\" .BR --cache-disable , .\" and .\" .B --cache-show .\" command-line options. The .\" .B --random .\" option is useful whenever multiple builds may be .\" trying to update the cache simultaneously. .B scons requires Python version 1.5.2 or later. There should be no other dependencies or requirements to run .B scons. The default .B scons configuration assumes use of the Microsoft Visual C++ compiler suite on WIN32 systems, and assumes a C compiler named .B cc and a C++ compiler named .B c++ (such as found in the GNU C compiler suite) on any other type of system. You may, of course, override these default values by appropriate configuration of Environment construction variables. .SH OPTIONS In general, .B scons supports the same command-line options as GNU .BR make , and many of those supported by .BR cons . .TP -b Ignored for compatibility with non-GNU versions of .BR make. .TP -c, --clean, --remove Clean up by removing all target files for which a construction command is specified. .\" .TP .\" --cache-disable, --no-cache .\" Disable caching. Will neither retrieve files from cache nor flush .\" files to cache. Has no effect if use of caching is not specified .\" in an SConscript file. .\" .\" .TP .\" --cache-force, --cache-populate .\" Populate a cache by forcing any already-existing up-to-date .\" target files to the cache, in addition to files built by this .\" invocation. This is useful to populate a new cache with .\" appropriate target files, or to make available in the cache .\" any target files recently built with caching disabled via the .\" .B --cache-disable .\" option. .\" .\" .TP .\" --cache-show .\" When retrieving a target file from a cache, show the command .\" that would have been executed to build the file. This produces .\" consistent output for build logs, regardless of whether a target .\" file was rebuilt or retrieved from cache. .TP .RI "-C" " directory" ", --directory=" directory Change to the specified .I directory before searching for the .IR SConstruct , .IR Sconstruct , or .I sconstruct file, or doing anything else. Multiple .B -C options are interpreted relative to the previous one, and the right-most .B -C option wins. (This option is nearly equivalent to .BR "-f directory/SConstruct" , except that it will search for .IR SConstruct , .IR Sconstruct , or .I sconstruct in the specified directory.) .\" .TP .\" -d .\" Display dependencies while building target files. Useful for .\" figuring out why a specific file is being rebuilt, as well as .\" general debugging of the build process. .TP -D Works exactly the same way as the .B -u option except for the way default targets are handled. When this option is used and no targets are specified on the command line, all default targets are built, whether or not they are below the current directory. .TP .RI --debug= type Debug the build process. .I type specifies what type of debugging: .TP .RI --debug=pdb Re-run SCons under the control of the .RI pdb Python debugger. The .RI --debug=pdb argument will be stripped from the command-line, but all other arguments will be passed in-order to the SCons invocation run by the debugger. .TP .RI --debug=tree Print the dependency tree after each top-level target is built. This prints out the complete dependency tree including implicit dependencies and ignored dependencies. .TP .RI --debug=dtree Print the dependency tree after each top-level target is built. This prints out only derived files. .TP .RI --debug=time Prints various time profiling information: the time spent executing each build command, the total build time, the total time spent executing build commands, the total time spent executing SConstruct and SConscript files, and the total time spent executing SCons itself. .TP -e, --environment-overrides Variables from the execution environment override construction variables from the SConscript files. .TP .RI -f " file" ", --file=" file ", --makefile=" file ", --sconstruct=" file Use .I file as the initial SConscript file. If .I file is in another directory, .B scons will change to that directory before building targets. .TP -h, --help Print a local help message for this build, if one is defined in the SConscript file(s), plus a line that describes the .B -H option for command-line option help. If no local help message is defined, prints the standard help message about command-line options. Exits after displaying the appropriate message. .TP -H, --help-options Print the standard help message about command-line options and exit. .TP -i, --ignore-errors Ignore all errors from commands executed to rebuild files. .TP .RI -I " directory" ", --include-dir=" directory Specifies a .I directory to search for imported Python modules. If several .B -I options are used, the directories are searched in the order specified. .TP --implicit-cache Cache implicit dependencies. This can cause .B scons to miss changes in the implicit dependencies in cases where a new implicit dependency is added earlier in the implicit dependency search path (e.g. CPPPATH) than a current implicit dependency with the same name. .TP --implicit-deps-changed Force SCons to ignore the cached implicit dependencies. This causes the implicit dependencies to be rescanned and recached. This implies .BR --implicit-cache . .TP --implicit-deps-unchanged Force SCons to ignore changes in the implicit dependencies. This causes cached implicit dependencies to always be used. This implies .BR --implicit-cache . .TP .RI -j " N" ", --jobs=" N Specifies the number of jobs (commands) to run simultaneously. If there is more than one .B -j option, the last one is effective. .\" ??? If the .\" .B -j .\" option .\" is specified without an argument, .\" .B scons .\" will not limit the number of .\" simultaneous jobs. .TP -k, --keep-going Continue as much as possible after an error. The target that failed and those that depend on it will not be remade, but other targets specified on the command line will still be processed. .\" .TP .\" .RI -l " N" ", --load-average=" N ", --max-load=" N .\" No new jobs (commands) will be started if .\" there are other jobs running and the system load .\" average is at least .\" .I N .\" (a floating-point number). .\" .\" .TP .\" --list-derived .\" List derived files (targets, dependencies) that would be built, .\" but do not build them. .\" [XXX This can probably go away with the right .\" combination of other options. Revisit this issue.] .\" .\" .TP .\" --list-actions .\" List derived files that would be built, with the actions .\" (commands) that build them. Does not build the files. .\" [XXX This can probably go away with the right .\" combination of other options. Revisit this issue.] .\" .\" .TP .\" --list-where .\" List derived files that would be built, plus where the file is .\" defined (file name and line number). Does not build the files. .\" [XXX This can probably go away with the right .\" combination of other options. Revisit this issue.] .TP -m Ignored for compatibility with non-GNU versions of .BR make . .TP .RI --max-drift= SECONDS Set the maximum expected drift in the modification time of files to .IR SECONDS . This value determines how old a file must be before its content signature is cached. The default value is 2 days, which means a file must have a modification time of at least two days ago in order to have its content signature cached. A negative value means to never cache the content signature and to ignore the cached value if there already is one. A value of 0 means to always cache the signature, no matter how old the file is. .TP -n, --just-print, --dry-run, --recon No execute. Print the commands that would be executed to build any out-of-date target files, but do not execute the commands. .\" .TP .\" .RI -o " file" ", --old-file=" file ", --assume-old=" file .\" Do not rebuild .\" .IR file , .\" and do .\" not rebuild anything due to changes in the contents of .\" .IR file . .\" .TP .\" .RI --override " file" .\" Read values to override specific build environment variables .\" from the specified .\" .IR file . .\" .TP .\" -p .\" Print the data base (construction environments, .\" Builder and Scanner objects) that are defined .\" after reading the SConscript files. .\" After printing, a normal build is performed .\" as usual, as specified by other command-line options. .\" This also prints version information .\" printed by the .\" .B -v .\" option. .\" .\" To print the database without performing a build do: .\" .\" .ES .\" scons -p -q .\" .EE .TP .RI --profile= file Run SCons under the Python profiler and save the results in the specified .IR file . The results may be analyzed using the Python pstats module. .TP -q, --question Do not run any commands, or print anything. Just return an exit status that is zero if the specified targets are already up to date, non-zero otherwise. .TP -Q Quiets SCons status messages about reading SConscript files, building targets and entering directories. Commands that are executed to rebuild target files are still printed. .\" .TP .\" -r, -R, --no-builtin-rules, --no-builtin-variables .\" Clear the default construction variables. Construction .\" environments that are created will be completely empty. .\" .\" .TP .\" --random .\" Build dependencies in a random order. This is useful when .\" building multiple trees simultaneously with caching enabled as a .\" way to prevent multiple builds from simultaneously trying to build .\" or retrieve the same target files. .TP -s, --silent, --quiet Silent. Do not print commands that are executed to rebuild target files. Also suppresses SCons status messages. .TP -S, --no-keep-going, --stop Ignored for compatibility with GNU .BR make . .TP -t, --touch Ignored for compatibility with GNU .BR make . (Touching a file to make it appear up-to-date is unnecessary when using .BR scons .) .TP -u, --up, --search-up Walks up the directory structure until an .I SConstruct , .I Sconstruct or .I sconstruct file is found, and uses that as the top of the directory tree. Only targets at or below the current directory will be built. .TP -U Works exactly the same way as the .B -u option except for the way default targets are handled. When this option is used and no targets are specified on the command line, all default targets that are defined in the SConscript(s) in the current directory are built, regardless of what directory the resultant targets end up in. .TP -v, --version Print the .B scons version, copyright information, list of authors, and any other relevant information. Then exit. .TP -w, --print-directory Print a message containing the working directory before and after other processing. .TP .RI --warn= type ", --warn=no-" type Enable or disable warnings. .I type specifies the type of warnings to be enabled or disabled: .TP .RI --warn=all ", " --warn=no-all Enables or disables all warnings. .TP .RI --warn=dependency ", " --warn=no-dependency Enables or disables warnings about dependencies. These warnings are disabled by default. .TP .RI --warn=deprecated ", " --warn=no-deprecated Enables or disables warnings about use of deprecated features. These warnings are enabled by default. .TP --no-print-directory Turn off -w, even if it was turned on implicitly. .\" .TP .\" .RI --write-filenames= file .\" Write all filenames considered into .\" .IR file . .\" .\" .TP .\" .RI -W " file" ", --what-if=" file ", --new-file=" file ", --assume-new=" file .\" Pretend that the target .\" .I file .\" has been .\" modified. When used with the .\" .B -n .\" option, this .\" show you what would be rebuilt if you were to modify that file. .\" Without .\" .B -n .\" ... what? XXX .\" .\" .TP .\" --warn-undefined-variables .\" Warn when an undefined variable is referenced. .TP .RI -Y " repository" ", --repository=" repository Search the specified repository for any input and target files not found in the local directory hierarchy. Multiple .B -Y options may specified, in which case the repositories are searched in the order specified. .SH CONFIGURATION FILE REFERENCE .\" .SS Python Basics .\" XXX Adding this in the future would be a help. .SS Construction Environments A construction environment is the basic means by which the SConscript files communicate build information to .BR scons . A new construction environment is created using the .B Environment function: .ES env = Environment() .EE By default, a new construction environment is initialized with a set of builder methods and construction variables that are appropriate for the current platform. An optional platform keyword argument may be used to specify that an environment should be initialized for a different platform: .ES env = Environment(platform = 'cygwin') env = Environment(platform = 'os2') env = Environment(platform = 'posix') env = Environment(platform = 'win32') .EE Specifying a platform initializes the appropriate construction variables in the environment to use and generate file names with prefixes and suffixes appropriate for the platform. The platform argument may be function or callable object, in which case the Environment() method will call the specified argument to update the new construction environment: .ES def my_platform(env): env['VAR'] = 'xyzzy' env = Environment(platform = my_platform) .EE Additionally, a specific set of tools with which to initialize the environment may specified as an optional keyword argument: .ES env = Environment(tools = ['msvc', 'lex']) .EE The elements of the tools list may also be functions or callable objects, in which case the Environment() method will call the specified elements to update the new construction environment: .ES def my_tool(env): env['XYZZY'] = 'xyzzy' env = Environment(tools = [my_tool]) .EE If no tool list is specified, then SCons will auto-detect the installed tools using the PATH variable in the ENV construction variable and the platform name when the Environment is constructed. Changing the PATH variable after the Environment is constructed will not cause the tools to be redetected. SCons supports the following tool specifications out of the box on all platforms: .ES ar dvipdf dvips g++ g77 icc ifl ilink gas gcc gnulink latex lex masm mslib mslink msvc nasm pdflatex pdftex tar tex yacc .EE On posix and cygwin platforms the GNU tools (e.g. gcc) are preferred by SCons, on win32 the Microsoft tools (e.g. msvc) are preferred by SCons, and in OS/2 the IBM tools (e.g. icc) are preferred by SCons. .SS Builder Methods Build rules are specified by calling a construction environment's builder methods. The arguments to the builder methods are .B target (a list of target files) and .B source (a list of source files). Because long lists of file names can lead to a lot of quoting, .B scons supplies a .B Split() function that splits a single string into a list, separated on strings of white-space characters. (This is similar to the string.split() method from the standard Python library.) Like all Python arguments, the target and source arguments to a builder can be specified either with or without the "target" and "source" keywords. When the keywords are omitted, the target is first, followed by the source. The following are equivalent examples of calling the Program builder: .ES env.Program('bar', ['bar.c', 'foo.c']) env.Program('bar', Split('bar.c foo.c')) env.Program(source = ['bar.c', 'foo.c'], target = 'bar') env.Program(target = 'bar', Split('bar.c foo.c')) env.Program('bar', source = string.split('bar.c foo.c')) .EE When the target shares the same base name as the source and only the suffix varies, and if the builder has a suffix defined for the target file type, then the target argument may be omitted completely, and .B scons will deduce the target file name from the source file name. The following examples all build the executable program .B bar (on POSIX systems) or .B bar.exe (on Windows systems) from the bar.c source file: .ES env.Program(target = 'bar', source = 'bar.c') env.Program('bar', source = 'bar.c') env.Program(source = 'bar.c') env.Program('bar.c') .EE It is possible to override or add construction variables when calling a builder by passing additional keyword arguments. These overriden or added variables will only be in effect when building the target, so they will not effect other parts of the build. For example, if you want to add additional libraries for just one program: .ES env.Program('hello', 'hello.c', LIBS=['gl', 'glut']) .EE or generate a shared library with a nonstandard suffix: .ES env.SharedLibrary('word', 'word.cpp', SHLIBSUFFIX='.ocx') .EE All Builders return a Node or a list of Nodes, representing the target or targets that will be built. A list of Nodes is returned if there is more than one target, and a single Node is returned if there is only one target. A .I Node is an internal SCons object which represents build targets or sources. The returned Node(s) can be passed to other builder methods as source(s) or passed into to any SCons function or method where a filename would normally be accepted. For example, if it were necessary to add a specific .B -D flag when compiling one specific object file: .ES bar_obj = env.StaticObject('bar.c', CCFLAGS='-DBAR') env.Program(source = ['foo.c', bar_obj, 'main.c']) .EE Using a Node in this way makes for a more portable build by avoiding having to specify a platform-specific object suffix when calling the Program() builder. The path name for a Node's file may be used by passing the Node to the Python-builtin .B str() function: .ES bar_obj = env.StaticObject('bar.c', CCFLAGS='-DBAR') print "The path to bar_obj is:", str(bar_obj) .B scons provides the following builders: .IP StaticObject Builds a static object file from one or more C, C++, or Fortran source files. Source files must have one of the following extensions: .ES .asm assembly language file .ASM assembly language file .c C file .C WIN32: C file POSIX: C++ file .cc C++ file .cpp C++ file .cxx C++ file .cxx C++ file .c++ C++ file .C++ C++ file .f Fortran file .F WIN32: Fortran file POSIX: Fortran file + C pre-processor .for Fortran file .FOR Fortran file .fpp Fortran file + C pre-processor .FPP Fortran file + C pre-processor .s assembly language file .S WIN32: assembly language file POSIX: assembly language file + C pre-processor .spp assembly language file + C pre-processor .SPP assembly language file + C pre-processor .EE .IP The target object file prefix (specified by the $OBJPREFIX construction variable; nothing by default) and suffix (specified by the $OBJSUFFIX construction variable; \.obj on Windows systems, .o on POSIX systems) are automatically added to the target if not already present. Examples: .ES env.StaticObject(target = 'aaa', source = 'aaa.c') env.StaticObject(target = 'bbb.o', source = 'bbb.c++') env.StaticObject(target = 'ccc.obj', source = 'ccc.f') .EE .IP SharedObject Builds an object file for inclusion in a shared library (that is, built with the '-fPIC' option when using gcc). Source files must have one of the same set of extensions specified above for the .B StaticObject builder. The target shared object file prefix (specified by the $SHOBJPREFIX construction variable; by default, the same as $OBJPREFIX) and suffix (specified by the $SHOBJSUFFIX construction variable; by default, the same as $OBJSUFFIX) are automatically added to the target if not already present. Examples: .ES env.SharedObject(target = 'ddd', source = 'ddd.c') env.SharedObject(target = 'eee.o', source = 'eee.cpp') env.SharedObject(target = 'fff.obj', source = 'fff.for') .EE .IP Object A synonym for the .B StaticObject builder. .IP PCH Builds a Microsoft Visual C++ precompiled header. Calling this builder returns a list of two targets: the PCH as the first element, and the object file as the second element. Normally the object file is ignored. This builder is only provided when Microsoft Visual C++ is being used as the compiler. The PCH builder is generally used in conjuction with the PCH construction variable to force object files to use the precompiled header: .ES env['PCH'] = env.PCH('StdAfx.cpp')[0] .EE .IP Program Builds an executable given one or more object files or C, C++ or Fortran source files. If any C, C++ or Fortran source files are specified, then they will be automatically compiled to object files using the .B Object builder; see that builder's description for a list of legal source file suffixes and how they are interpreted. The target executable file prefix (specified by the $PROGPREFIX construction variable; nothing by default) and suffix (specified by the $PROGSUFFIX construction variable; by default, .exe on Windows systems, nothing on POSIX systems) are automatically added to the target if not already present. Example: .ES env.Program(target = 'foo', source = ['foo.o', 'bar.c', 'baz.f']) .EE .IP RES Builds a Microsoft Visual C++ resource file. This builder is only provided when Microsoft Visual C++ is being used as the compiler. The .I .res suffix is added to the target name if no other suffix is given. The source file is scanned for implicit dependencies as though it were a C file. Example: .ES env.RES('resource.rc') .EE .IP StaticLibrary Builds a static library given one or more object files or C, C++ or Fortran source files. If any source files are given, then they will be automatically compiled to object files. The static library prefix and suffix (if any) are automatically added to the target. The target library file prefix (specified by the $LIBPREFIX construction variable; by default, lib on POSIX systems, nothing on Windows systems) and suffix (specified by the $LIBSUFFIX construction variable; by default, .lib on Windows systems, .a on POSIX systems) are automatically added to the target if not already present. Example: .ES env.StaticLibrary(target = 'bar', source = ['bar.c', 'foo.o']) .EE .IP Any object files listed in the .B source must have been built for a static library (that is, using the .B StaticObject builder). .B scons will raise an error if there is any mismatch. .IP SharedLibrary Builds a shared library (.so on a POSIX system, .dll on WIN32) given one or more object files or C, C++ or Fortran source files. If any source files are given, then they will be automatically compiled to object files. The static library prefix and suffix (if any) are automatically added to the target. The target library file prefix (specified by the $SHLIBPREFIX construction variable; by default, lib on POSIX systems, nothing on Windows systems) and suffix (specified by the $SHLIBSUFFIX construction variable; by default, .dll on Windows systems, .so on POSIX systems) are automatically added to the target if not already present. Example: .ES env.SharedLibrary(target = 'bar', source = ['bar.c', 'foo.o']) .EE .IP On WIN32 systems, the .B SharedLibrary builder will always build an import (.lib) library in addition to the shared (.dll) library, adding a .lib library with the same basename if there is not already a .lib file explicitly listed in the targets. Any object files listed in the .B source must have been built for a shared library (that is, using the .B SharedObject builder). .B scons will raise an error if there is any mismatch. .IP Library A synonym for the .B StaticLibrary builder. .IP CFile Builds a C source file given a lex (.l) or yacc (.y) input file. The suffix specified by the $CFILESUFFIX construction variable (.c by default) is automatically added to the target if it is not already present. Example: .ES # builds foo.c env.CFile(target = 'foo.c', source = 'foo.l') # builds bar.c env.CFile(target = 'bar', source = 'bar.y') .EE .IP CXXFile Builds a C++ source file given a lex (.ll) or yacc (.yy) input file. The suffix specified by the $CXXFILESUFFIX construction variable (.cc by default) is automatically added to the target if it is not already present. Example: .ES # builds foo.cc env.CXXFile(target = 'foo.cc', source = 'foo.ll') # builds bar.cc env.CXXFile(target = 'bar', source = 'bar.yy') .EE .IP DVI Builds a .dvi file from a .tex, .ltx or .latex input file. The suffix .dvi (hard-coded within TeX itself) is automatically added to the target if it is not already present. Example: .ES # builds from aaa.tex env.DVI(target = 'aaa.dvi', source = 'aaa.tex') # builds bbb.dvi env.DVI(target = 'bbb', source = 'bbb.ltx') # builds from ccc.latex env.DVI(target = 'ccc.dvi', source = 'ccc.latex') .EE .IP PDF Builds a .pdf file from a .dvi input file (or, by extension, a .tex, .ltx, or .latex input file). The suffix specified by the $PDFSUFFIX construction variable (.pdf by default) is added automatically to the target if it is not already present. Example: .ES # builds from aaa.tex env.PDF(target = 'aaa.pdf', source = 'aaa.tex') # builds bbb.pdf from bbb.dvi env.PDF(target = 'bbb', source = 'bbb.dvi') .EE .IP PostScript Builds a .ps file from a .dvi input file (or, by extension, a .tex, .ltx, or .latex input file). The suffix specified by the $PSSUFFIX construction variable (.ps by default) is added automatically to the target if it is not already present. Example: .ES # builds from aaa.tex env.PostScript(target = 'aaa.ps', source = 'aaa.tex') # builds bbb.ps from bbb.dvi env.PostScript(target = 'bbb', source = 'bbb.dvi') .EE .LP .B scons automatically scans C source files, C++ source files, Fortran source files with .B .F (POSIX systems only), .B .fpp, or .B .FPP file extensions, and assembly language files with .B .S (POSIX systems only), .B .spp, or .B .SPP files extensions for C preprocessor dependencies, so the dependencies do not need to be specified explicitly. In addition, all builder targets automatically depend on their sources. An explicit dependency can be specified using the .B Depends method of a construction environment (see below). .SS Other Construction Environment Methods Additional construction environment methods include: .TP .RI Alias( alias ", " targets ) Creates a phony target that expands to one or more other targets. Returns the Node object representing the alias, which exists outside of any file system. This Node object, or the alias name, may be used as a dependency of any other target, including another alias. Alias can be called multiple times for the same alias to add additional targets to the alias. .ES env.Alias('install', ['/usr/local/bin', '/usr/local/lib']) env.Alias('install', ['/usr/local/man']) .EE .TP .RI Append( key = val ", [...])" Appends the specified keyword arguments to the end of construction variables in the environment. If the Environment does not have the specified construction variable, it is simply added to the environment. If the values of the construction variable and the keyword argument are the same type, then the two values will be simply added together. Otherwise, the construction variable and the value of the keyword argument are both coerced to lists, and the lists are added together. (See also the Prepend method, below.) .ES env.Append(CCFLAGS = ' -g', FOO = ['foo.yyy']) .EE .TP .RI Command( target ", " source ", " commands ) Executes a specific action (or list of actions) to build a target file or files. This is more convenient than defining a separate Builder object for a single special-case build. Note that an action can be an external command, specified as a string, or a callable Python object; see "Action Objects," below. Examples: .ES env.Command('foo.out', 'foo.in', "$FOO_BUILD < $SOURCES > $TARGET") env.Command('bar.out', 'bar.in', ["rm -f $TARGET", "$BAR_BUILD < $SOURCES > $TARGET"]) def rename(env, target, source): import os os.rename('.tmp', str(target[0])) env.Command('baz.out', 'baz.in', ["$BAZ_BUILD < $SOURCES > .tmp", rename ]) .EE .TP .RI Copy([ key = val ", ...])" Return a separate copy of a construction environment. If there are any keyword arguments specified, they are added to the returned copy, overwriting any existing values for the keywords. .ES env2 = env.Copy() env3 = env.Copy(CCFLAGS = '-g') .EE .TP .RI Depends( target ", " dependency ) Specifies an explicit dependency; the target file(s) will be rebuilt whenever the dependency file(s) has changed. This should only be necessary for cases where the dependency is not caught by a Scanner for the file. .ES env.Depends('foo', 'other-input-file-for-foo') .EE .TP .RI Dictionary([ vars ]) Returns a dictionary object containing copies of all of the construction variables in the environment. If there are any variable names specified, only the specified construction variables are returned in the dictionary. .ES dict = env.Dictionary() cc_dict = env.Dictionary('CC', 'CCFLAGS', 'CCCOM') .EE .TP .RI Ignore( target ", " dependency ) The specified dependency file(s) will be ignored when deciding if the target file(s) need to be rebuilt. .ES env.Ignore('foo', 'foo.c') env.Ignore('bar', ['bar1.h', 'bar2.h']) .EE .TP .RI Install( dir ", " source ) Installs one or more files in a destination directory. The file names remain the same. .ES env.Install(dir = '/usr/local/bin', source = 'foo bar') .EE .TP .RI InstallAs( target ", " source ) Installs one or more files as specific file names, allowing changing a file name as part of the installation. It is an error if the target and source list different numbers of files. .ES env.InstallAs(target = '/usr/local/bin/foo', source = 'foo_debug') env.InstallAs(target = '../lib/libfoo.a ../lib/libbar.a', source = 'libFOO.a libBAR.a') .EE .TP .RI Precious( target ", ...)" Marks each given .I target as precious so it is not deleted before it is rebuilt. Normally .B scons deletes a target before building it. Multiple targets can be passed in to a single call to .BR Precious (). .TP .RI Prepend( key = val ", [...])" Appends the specified keyword arguments to the beginning of construction variables in the environment. If the Environment does not have the specified construction variable, it is simply added to the environment. If the values of the construction variable and the keyword argument are the same type, then the two values will be simply added together. Otherwise, the construction variable and the value of the keyword argument are both coerced to lists, and the lists are added together. (See also the Append method, above.) .ES env.Prepend(CCFLAGS = '-g ', FOO = ['foo.yyy']) .EE .TP .RI Replace( key = val ", [...])" Replaces construction variables in the Environment with the specified keyword arguments. (Note: "Update()" is a deprecated synonym for this method.) .ES env.Replace(CCFLAGS = '-g', FOO = 'foo.xxx') .EE .TP .RI SideEffect( side_effect , target ) Declares .I side_effect as a side effect of building .IR target . Both .I side_effect and .I target can be a list, a file name, or a node. A side effect is a target that is created as a side effect of building other targets. For example, a Windows PDB file is created as a side effect of building the .obj files for a static library. If a target is a side effect of multiple build commands, .B scons will ensure that only one set of commands is executed at a time. Consequently, you only need to use this method for side-effect targets that are built as a result of multiple build commands. .SS Construction Variables .\" XXX From Gary Ruben, 23 April 2002: .\" I think it would be good to have an example with each construction .\" variable description in the documentation. .\" eg. .\" CC The C compiler .\" Example: env["CC"] = "c68x" .\" Default: env["CC"] = "cc" .\" .\" CCCOM The command line ... .\" Example: .\" To generate the compiler line c68x -ps -qq -mr -o $TARGET $SOURCES .\" env["CC"] = "c68x" .\" env["CFLAGS"] = "-ps -qq -mr" .\" env["CCCOM"] = "$CC $CFLAGS -o $TARGET $SOURCES .\" Default: .\" (I dunno what this is ;-) A construction environment has an associated dictionary of construction variables that are used by built-in or user-supplied build rules. A number of useful construction variables are automatically defined by scons for each supported platform, and additional construction variables can be defined by the user. The following is a list of the automatically defined construction variables: .IP AR The static library archiver. .IP ARCOM The command line used to generate a static library from object files. .IP ARFLAGS General options passed to the static library archiver. .IP AS The assembler. .IP ASCOM The command line used to generate an object file from an assembly-language source file. .IP ASFLAGS General options passed to the assembler. .IP ASPPCOM The command line used to assemble an assembly-language source file into an object file after first running the file through the C preprocessor. Any options specified in the $ASFLAGS and $CPPFLAGS construction variables are included on this command line. .IP BUILDERS A dictionary mapping the names of the builders available through this environment to underlying Builder objects. Builders named Alias, CFile, CXXFile, DVI, Library, Object, PDF, PostScript, and Program are available by default. .IP CC The C compiler. .IP CCCOM The command line used to compile a C source file to a (static) object file. Any options specified in the $CCFLAGS and $CPPFLAGS construction variables are included on this command line. .IP CCFLAGS General options that are passed to the C compiler. .IP CFILESUFFIX The suffix for C source files. This is used by the internal CFile builder when generating C files from Lex (.l) or YACC (.y) input files. The default suffix, of course, is .I .c (lower case). On case-insensitive systems (like Win32), SCons also treats .I .C (upper case) files as C files. .IP _concat A function used to produce variables like $_CPPINCFLAGS. It takes six arguments: a prefix to concatenate onto each element, a list of elements, a suffix to concatenate onto each element, a dictionary of global variables for variable interpolation, a list of local variables for variable interpolation, and an optional function that will be called to transform the list before concatenation. .ES env['_CPPINCFLAGS'] = '$( ${_concat(INCPREFIX, CPPPATH, INCSUFFIX, locals(), globals(), RDirs)} $)', .EE .IP CPPFLAGS C preprocessor options. These will be included in any command that uses the C preprocessor, including not just compilation of C and C++ source files via the $CCCOM, $SHCCCOM, $CXXCOM and $SHCXXCOM command lines, but also the $F77PPCOM command line used to compile a Fortran source file, and the $ASPPCOM command line used to assemble an assembly language source file, after first running each file through the C preprocessor. .IP _CPPINCFLAGS An automatically-generated construction variable containing the C preprocessor command-line options for specifying directories to be searched for include files. The value of $_CPPINCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $CPPPATH. .IP CPPPATH The list of directories that the C preprocessor will search for include directories. The C/C++ implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in CCFLAGS or CXXFLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in CPPPATH will be looked-up relative to the SConscript directory when they are used in a command. To force .B scons to look-up a directory relative to the root of the source tree use #: .ES env = Environment(CPPPATH='#/include') .EE .IP The directory look-up can also be forced using the .BR Dir () function: .ES include = Dir('include') env = Environment(CPPPATH=include) .EE .IP The directory list will be added to command lines through the automatically-generated $_CPPINCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $CPPPATH. Any command lines you define that need the CPPPATH directory list should include $_CPPINCFLAGS: .ES env = Environment(CCCOM="my_compiler $_CPPINCFLAGS -c -o $TARGET $SOURCE") .EE .IP CXX The C++ compiler. .IP CXXFILESUFFIX The suffix for C++ source files. This is used by the internal CXXFile builder when generating C++ files from Lex (.ll) or YACC (.yy) input files. The default suffix is .IR .cc . SCons also treats files with the suffixes .IR .cpp , .IR .cxx , .IR .c++ , and .I .C++ as C++ files. On case-sensitive systems (Linux, UNIX, and other POSIX-alikes), SCons also treats .I .C (upper case) files as C++ files. .IP CXXCOM The command line used to compile a C++ source file to an object file. Any options specified in the $CXXFLAGS and $CPPFLAGS construction variables are included on this command line. .IP CXXFLAGS General options that are passed to the C++ compiler. .IP Dir A function that converts a file name into a Dir instance relative to the target being built. .IP DVIPDF The TeX DVI file to PDF file converter. .IP DVIPDFFLAGS General options passed to the TeX DVI file to PDF file converter. .IP DVIPS The TeX DVI file to PostScript converter. .IP DVIPSFLAGS General options passed to the TeX DVI file to PostScript converter. .IP ENV A dictionary of environment variables to use when invoking commands. Note that, by default, .B scons does .I not propagate the environment in force when you execute .B scons to the commands used to build target files. This is so that builds will be guaranteed repeatable regardless of the environment variables set at the time .B scons is invoked. If you want to propagate your environment variables to the commands executed to build target files, you must do so explicitly: .ES import os env = Environment(ENV = os.environ) .EE .RS Note that you can choose only to propagate certain environment variables. A common example is the system .B PATH environment variable, so that .B scons uses the same utilities as the invoking shell (or other process): .RE .ES import os env = Environment(ENV = {'PATH' : os.environ['PATH']}) .EE .IP ESCAPE A function that will be called to escape shell special characters in command lines. The function should take one argument: the command line string to escape; and should return the escaped command line. .IP F77 The Fortran compiler. .IP F77COM The command line used to compile a Fortran source file to an object file. .IP F77FLAGS General options that are passed to the Fortran compiler. .IP _F77INCFLAGS An automatically-generated construction variable containing the Fortran compiler command-line options for specifying directories to be searched for include files. The value of $_F77INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $F77PATH. .IP F77PATH The list of directories that the Fortran compiler will search for include directories. The Fortran implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in F77FLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in F77PATH will be looked-up relative to the SConscript directory when they are used in a command. To force .B scons to look-up a directory relative to the root of the source tree use #: .ES env = Environment(F77PATH='#/include') .EE .IP The directory look-up can also be forced using the .BR Dir () function: .ES include = Dir('include') env = Environment(F77PATH=include) .EE .IP The directory list will be added to command lines through the automatically-generated $_F77INCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $F77PATH. Any command lines you define that need the F77PATH directory list should include $_F77INCFLAGS: .ES env = Environment(F77COM="my_compiler $_F77INCFLAGS -c -o $TARGET $SOURCE") .EE .IP F77PPCOM The command line used to compile a Fortran source file to an object file after first running the file through the C preprocessor. Any options specified in the $F77FLAGS and $CPPFLAGS construction variables are included on this command line. .IP File A function that converts a file name into a File instance relative to the target being built. .IP INCPREFIX The prefix used to specify an include directory on the C compiler command line. This will be appended to the beginning of each directory in the $CPPPATH and $F77PATH construction variables when the $_CPPINCFLAGS and $_F77INCFLAGS variables are automatically generated. .IP INCSUFFIX The suffix used to specify an include directory on the C compiler command line. This will be appended to the end of each directory in the $CPPPATH and $F77PATH construction variables when the $_CPPINCFLAGS and $_F77INCFLAGS variables are automatically generated. .IP LATEX The LaTeX structured formatter and typesetter. .IP LATEXCOM The command line used to call the LaTeX structured formatter and typesetter. .IP LATEXFLAGS General options passed to the LaTeX structured formatter and typesetter. .IP LEX The lexical analyzer generator. .IP LEXFLAGS General options passed to the lexical analyzer generator. .IP LEXCOM The command line used to call the lexical analyzer generator to generate a source file. .IP _LIBDIRFLAGS An automatically-generated construction variable containing the linker command-line options for specifying directories to be searched for library. The value of $_LIBDIRFLAGS is created by appending $LIBDIRPREFIX and $LIBDIRSUFFIX to the beginning and end of each directory in $LIBPATH. .IP LIBDIRPREFIX The prefix used to specify a library directory on the linker command line. This will be appended to the beginning of each directory in the $LIBPATH construction variable when the $_LIBDIRFLAGS variable is automatically generated. .IP LIBDIRSUFFIX The suffix used to specify a library directory on the linker command line. This will be appended to the end of each directory in the $LIBPATH construction variable when the $_LIBDIRFLAGS variable is automatically generated. .IP _LIBFLAGS An automatically-generated construction variable containing the linker command-line options for specifying libraries to be linked with the resulting target. The value of $_LIBFLAGS is created by appending $LIBLINKPREFIX and $LIBLINKSUFFIX to the beginning and end of each directory in $LIBS. .IP LIBLINKPREFIX The prefix used to specify a library to link on the linker command line. This will be appended to the beginning of each library in the $LIBS construction variable when the $_LIBFLAGS variable is automatically generated. .IP LIBLINKSUFFIX The suffix used to specify a library to link on the linker command line. This will be appended to the end of each library in the $LIBS construction variable when the $_LIBFLAGS variable is automatically generated. .IP LIBPATH The list of directories that will be searched for libraries. The implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in LINKFLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in LIBPATH will be looked-up relative to the SConscript directory when they are used in a command. To force .B scons to look-up a directory relative to the root of the source tree use #: .ES env = Environment(LIBPATH='#/libs') .EE .IP The directory look-up can also be forced using the .BR Dir () function: .ES libs = Dir('libs') env = Environment(LIBPATH=libs) .EE .IP The directory list will be added to command lines through the automatically-generated $_LIBDIRFLAGS construction variable, which is constructed by appending the values of the $LIBDIRPREFIX and $LIBDIRSUFFIX construction variables to the beginning and end of each directory in $LIBPATH. Any command lines you define that need the LIBPATH directory list should include $_LIBDIRFLAGS: .ES env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE") .EE .IP LIBPREFIX The prefix used for (static) library file names. .IP LIBPREFIXES An array of legal prefixes for library file names. .IP LIBS A list of one or more libraries that will be linked with any executable programs created by this environment. .IP The library list will be added to command lines through the automatically-generated $_LIBFLAGS construction variable, which is constructed by appending the values of the $LIBLINKPREFIX and $LIBLINKSUFFIX construction variables to the beginning and end of each directory in $LIBS. Any command lines you define that need the LIBS library list should include $_LIBFLAGS: .ES env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE") .EE .IP LIBSUFFIX The suffix used for (static) library file names. .IP LIBSUFFIXES An array of legal suffixes for library file names. .IP LINK The linker. .IP LINKFLAGS General options passed to the linker. .IP LINKCOM The command line used to link object files into an executable. .IP OBJPREFIX The prefix used for (static) object file names. .IP OBJSUFFIX The suffix used for (static) object file names. .IP PCH The Microsoft Visual C++ precompiled header that will be used when compiling object files. This variable is ignored by tools other than Microsoft Visual C++. When this variable is defined SCons will add options to the compiler command line to cause it to use the precompiled header, and will also set up the dependencies for the PCH file. Example: .ES env['PCH'] = 'StdAfx.pch' .EE .IP PCHSTOP This variable specifies how much of a source file is precompiled. This variable is ignored by tools other than Microsoft Visual C++, or when the PCH variable is not being used. When this variable is define it must be a string that is the name of the header that is included at the end of the precompiled portion of the source files, or the empty string if the "#pragma hrdstop" construct is being used: .ES env['PCHSTOP'] = 'StdAfx.h' .EE .IP PDB The Microsoft Visual C++ PDB file that will store debugging information for object files, shared libraries, and programs. This variable is ignored by tools other than Microsoft Visual C++. When this variable is defined SCons will add options to the compiler and linker command line to cause them to generate external debugging information, and will also set up the dependencies for the PDB file. Example: .ES env['PDB'] = 'hello.pdb' .EE .IP PDFCOM The command line used to convert TeX DVI files into a PDF file. .IP PDFPREFIX The prefix used for PDF file names. .IP PDFSUFFIX The suffix used for PDF file names. .IP PROGPREFIX The prefix used for executable file names. .IP PROGSUFFIX The suffix used for executable file names. .IP PSCOM The command line used to convert TeX DVI files into a PostScript file. .IP PSPREFIX The prefix used for PostScript file names. .IP PSSUFFIX The prefix used for PostScript file names. .IP RANLIB The archive indexer. .IP RANLIBFLAGS General options passed to the archive indexer. .IP RC The resource compiler used by the RES builder. .IP RCCOM The command line used by the RES builder. .IP RCFLAGS The flags passed to the resource compiler by the RES builder. .IP RDirs A function that converts a file name into a list of Dir instances by searching the repositories. .IP SCANNERS A list of the available implicit dependency scanners. [CScan] by default. .IP SHCC The C compiler used for generating shared-library objects. .IP SHCCCOM The command line used to compile a C source file to a shared-library object file. Any options specified in the $SHCCFLAGS and $CPPFLAGS construction variables are included on this command line. .IP SHCCFLAGS Options that are passed to the C compiler to generate shared-library objects. .IP SHCXX The C++ compiler used for generating shared-library objects. .IP SHCXXCOM The command line used to compile a C++ source file to a shared-library object file. Any options specified in the $SHCXXFLAGS and $CPPFLAGS construction variables are included on this command line. .IP SHCXXFLAGS Options that are passed to the C++ compiler to generate shared-library objects. .IP SHELL A string naming the shell program that will be passed to the .I SPAWN function. See the .I SPAWN construction variable for more information. .IP SHF77 The Fortran compiler used for generating shared-library objects. .IP SHF77COM The command line used to compile a Fortran source file to a shared-library object file. .IP SHF77FLAGS Options that are passed to the Fortran compiler to generated shared-library objects. .IP SHF77PPCOM The command line used to compile a Fortran source file to a shared-library object file after first running the file through the C preprocessor. Any options specified in the $SHF77FLAGS and $CPPFLAGS construction variables are included on this command line. .IP SHLIBPREFIX The prefix used for shared library file names. .IP SHLIBSUFFIX The suffix used for shared library file names. .IP SHLINK The linker for programs that use shared libraries. .IP SHLINKFLAGS General options passed to the linker for programs using shared libraries. .IP SHOBJPREFIX The prefix used for shared object file names. .IP SHOBJSUFFIX The suffix used for shared object file names. .IP SPAWN A command interpreter function that will be called to execute command line strings. The function must expect 4 arguments: .ES def spawn(shell, escape, cmd, args, env): .EE .IP .I sh is a string naming the shell program to use. .I escape is a function that can be called to escape shell special characters in the command line. .I cmd is the path to the command to be executed. .I args is that arguments to the command. .I env is a dictionary of the environment variables in which the command should be executed. .IP TAR The tar archiver. .IP TARCOM The command line used to call the tar archiver. .IP TARFLAGS General options passed to the tar archiver. .IP TARSUFFIX The suffix used for tar file names. .IP TEX The TeX formatter and typesetter. .IP TEXCOM The command line used to call the TeX formatter and typesetter. .IP TEXFLAGS General options passed to the TeX formatter and typesetter. .IP WIN32_INSERT_DEF When this is set to true, a library build of a WIN32 shared library (.dll file) will also build a corresponding .def file at the same time, if a .def file is not already listed as a build target. The default is 0 (do not build a .def file). .IP WIN32DEFPREFIX The prefix used to build WIN32 .def files. .IP WIN32DEFSUFFIX The suffix used for WIN32 .def file names. .IP WIN32DLLPREFIX The prefix used to build WIN32 shared libraries (.dll files). .IP WIN32IMPLIBPREFIX The prefix used to build WIN32 import libraries. .IP YACC The parser generator. .IP YACCCOM The command line used to call the parser generator to generate a source file. .IP YACCFLAGS General options passed to the parser generator. .LP Construction variables can be retrieved and set using the .B Dictionary method of the construction environment: .ES dict = env.Dictionary() dict["CC"] = "cc" .EE or using the [] operator: .ES env["CC"] = "cc" .EE Construction variables can also be passed to the construction environment constructor: .ES env = Environment(CC="cc") .EE or when copying a construction environment using the .B Copy method: .ES env2 = env.Copy(CC="cl.exe") .EE .SS Costruction Variable Options Often when building software, various options need to be specified at build time that are not known when the SConstruct/SConscript files are written. For example, libraries needed for the build may be in non-standard locations, or site-specific compiler options may need to be passed to the compiler. .B scons provides a mechanism for overridding construction variables from the command line or a text-based SConscript file through an Options object. To create an Options object, call the Options() function: .TP .RI Options([ file ]) This creates an Options object that will read construction variables from the filename based in the .I file argument. If no filename is given, then no file will be read. Example: .ES opts = Options('custom.py') .EE Options objects have the following methods: .TP .RI Add( key ", [" help ", " default ", " validater ", " converter ]) This adds a customizable construction variable to the Options object. .I key is the name of the variable. .I help is the help text for the variable. .I default is the default value of the variable. .I validater is called to validate the value of the variable, and should take two arguments: key and value. .I converter is called to convert the value before putting it in the environment, and should take a single argument: value. Example: .ES opts.Add('CC', 'The C compiler') .EE .TP .RI Update( env ) This updates a construction environment .I env with the customized construction variables. Normally this method is not called directly, but is called indirectly by passing the Options object to the Environment() function: .ES env = Environment(options=opts) .EE .TP .RI GenerateHelpText( env ) This generates help text documenting the customizable construction variables suitable to passing in to the Help() function. .I env is the construction environment that will be used to get the actual values of customizable variables. Example: .ES Help(opts.GenerateHelpText(env)) .EE The text based SConscript file is executed as a Python script, and the global variables are queried for customizable construction variables. Example: .ES CC = 'my_cc' .EE .SS Other Functions .B scons also provides various additional functions, not associated with a construction environment, that SConscript files can use: .TP .RI BuildDir( build_dir ", " src_dir ", [" duplicate ]) This specifies a build directory to use for all derived files. .I build_dir specifies the build directory to be used for all derived files that would normally be built under .IR src_dir . Multiple build directories can be set up for multiple build variants, for example. .I src_dir must be underneath the SConstruct file's directory, and .I build_dir may not be underneath the .I src_dir . .B scons will link or copy (depending on the platform) all the source files into the build directory if .I duplicate is set to 1 (the default). If .I duplicate is set to 0, then .B scons will not copy or link any source files, which may cause build problems in certain situations (e.g. C source files that are generated by the build). .IR duplicate =0 is usually safe, and is always more efficient than .IR duplicate =1. .TP .RI Default( targets ) This specifies a list of default targets, which will be built by .B scons if no explicit targets are given on the command line. Multiple calls to .BR Default () are legal, and add to the list of default targets. Multiple targets should be specified as separate arguments to the .BR Default () method or as a list. .BR Default () will also accept the return value of any of the construction environment builder methods. Examples: .ES Default('foo', 'bar', 'baz') Default(['a', 'b', 'c']) Default(env.Program('hello', 'hello.c')) .EE .TP .RI Dir( name ", [" directory ]) This returns an object that represents a given directory .IR name . .I name can be a relative or absolute path. .I directory is an optional directory that will be used as the parent directory. .TP .RI EnsurePythonVersion( major ", " minor ) Ensure that the Python version is at least .IR major . minor . This function will print out an error message and exit SCons with a non-zero exit code if the actual Python version is not late enough. .ES EnsurePythonVersion(2,2) .EE .TP .RI EnsureSConsVersion( major ", " minor ) Ensure that the SCons version is at least .IR major . minor . This function will print out an error message and exit SCons with a non-zero exit code if the actual SCons version is not late enough. .ES EnsureSConsVersion(0,9) .EE .TP .RI Export( vars ) This tells .B scons to export a list of variables from the current SConscript file to all other SConscript files. The exported variables are kept in a global collection, so subsequent exports will over-write previous exports that have the same name. Multiple variable names should be passed to .BR Export () as separate arguments. Examples: .ES Export("env") Export("env", "variable") .EE .TP .RI File( name ", [" directory ]) This returns an object that represents a given file .IR name . .I name can be a relative or absolute path. .I directory is an optional directory that will be used as the parent directory. .TP .RI FindFile( file ", " dirs ) Search for .I file in the path specified by .IR dirs . .I file may be a list of file names or a single file name. In addition to searching for files that exist in the filesytem, this function also searches for derived files that have not yet been built. .ES foo = FindFile('foo', ['dir1', 'dir2']) .EE .\" .\".TP .\".RI GetBuildPath( XXX ) .\"XXX .\" .\".TP .\".RI GetLaunchDir( XXX ) .\"XXX .TP .RI GetJobs() Get the number of jobs (commands) that will be run simultaneously. See also .I -j and .IR SetJobs() . .TP .RI Help( text ) This specifies help text to be printed if the .B -h argument is given to .BR scons . .B scons will exit after printing out the help text. .TP .RI Import( vars ) This tells .B scons to import a list of variables into the current SConscript file. This will import variables that were exported with .BR Export () or in the .I exports argument to .BR SConscript (). Variables exported by .BR SConscript () have precedence. Multiple variable names should be passed to .BR Import () as separate arguments. Examples: .ES Import("env") Import("env", "variable") .EE .TP .RI Literal( string ) The specified .I string will be preserved as-is and not have construction variables expanded. .TP .RI Local( targets ) The specified .I targets will have copies made in the local tree, even if an already up-to-date copy exists in a repository. .TP .RI ParseConfig( env , command ", [" function ]) Calls the specified .I function to modify the specified environment .I env as specified by the output of .I command . The default .I function expects the output of a typical .I *-config command (for example, .BR gtk-config ) and parses the returned .BR -L , .BR -l , .B -I and other options into the .BR LIBPATH , .BR LIBS , .B CPPPATH and .B CCFLAGS variables, respectively. .TP .RI Platform( string ) Returns a callable object that can be used to initialize a construction environment using the platform keyword of the Environment() method. .ES env = Environment(platform = Platform('win32')) .EE .TP .RI Repository( directory ) Specifies that .I directory is a repository to be searched for files. Multiple calls to .BR Repository () are legal, and each one adds to the list of repositories that will be searched. To .BR scons , a repository is a copy of the source tree, from the top-level directory on down, which may contain both source files and derived files that can be used to build targets in the local source tree. The canonical example would be an official source tree maintained by an integrator. If the repository contains derived files, then the derived files should have been built using .BR scons , so that the repository contains the necessary signature information to allow .B scons to figure out when it is appropriate to use the repository copy of a derived file, instead of building one locally. Note that if an up-to-date derived file already exists in a repository, .B scons will .I not make a copy in the local directory tree. In order to guarantee that a local copy will be made, use the .B Local() method. .TP .RI Return( vars ) This tells .B scons what variable(s) to use as the return value(s) of the current SConscript file. These variables will be returned to the "calling" SConscript file as the return value(s) of .BR SConscript (). Multiple variable names should be passed to .BR Return () as a list. Example: .ES Return("foo") Return(["foo", "bar"]) .EE .TP .RI SConscript( script ", [" exports ]) This tells .B scons to execute .I script as a SConscript (configuration) file. The optional .I exports argument provides a list of variable names to export to .IR script ". " .I script must use the .BR Import () function to import the variables. Any variables returned by .I script using .BR Return () will be returned by the call to .BR SConscript (). Examples: .ES SConscript('dir/SConscript') foo = SConscript('subdir/SConscript', "env") .EE .TP .RI SConscriptChdir( value ) When a non-zero .I value is specified, this instructs .B scons to change its working directory (chdir) to the directory in which each subsidiary SConscript file lives. Note that you may enable and disable this ability by calling SConscriptChdir() multiple times: .ES SConscriptChdir(1) SConscript('foo/SConscript') # will chdir to foo SConscriptChdir(0) SConscript('bar/SConscript') # will not chdir to bar .EE .TP .RI SetBuildSignatureType( type ) This function tells SCons what type of build signature to use: "build" or "content". "build" means to concatenate the signatures of all source files of a derived file to make its signature, and "content" means to use the derived files content signature as its signature. "build" signatures are usually faster to compute, but "content" signatures can prevent redundant rebuilds. The default is "build". .TP .RI SetContentSignatureType( type ) This function tells SCons what type of content signature to use: "MD5" or "timestamp". "MD5" means to use the MD5 checksum of a files contents as its signature, and "timestamp" means to use a files timestamp as its signature. When using "timestamp" signatures, changes in the command line will not cause files to be rebuilt. "MD5" signatures take longer to compute, but "timestamp" signatures are less accurate. The default is "MD5". .TP .RI SetJobs( num ) Specifies the number of jobs (commands) to run simultaneously. .I -j overrides this function. See also .I -j and .IR GetJobs() . .TP .RI Split( arg ) Returns a list of file names or other objects. If arg is a string, it will be split on strings of white-space characters within the string, making it easier to write long lists of file names. If arg is already a list, the list will be returned untouched. If arg is any other type of object, it will be returned as a list containing just the object. .ES files = Split("f1.c f2.c f3.c") files = Split(""" f4.c f5.c f6.c """) .EE .TP .RI Tool( string ) Returns a callable object that can be used to initialize a construction environment using the tools keyword of the Environment() method. .ES env = Environment(tools = [ Tool('msvc') ]) .EE .TP .RI WhereIs( program ", [" path ", [" pathext ]]) Searches for the specified executable .I program, returning the full path name to the program if it is found, and returning None if not. Searches the specified .I path, or the user's current PATH (os.environ['PATH']) by default. On Win32 systems, searches for executable programs with any of the file extensions listed in the specified .I pathext, or the user's current PATHEXT (os.environ['PATHEXT']) by default. .SH EXTENDING SCONS .SS Builder Objects .B scons can be extended by adding new builders to a construction environment using the .B Builder function. The .B Builder function accepts the following arguments: .IP name The name of the builder. This will be the name of the construction environment method used to create an instance of the builder. .IP action The command line string used to build the target from the source. .B action can also be: a list of strings representing the command to be executed and its arguments (suitable for enclosing white space in an argument), a dictionary mapping source file name suffixes to any combination of command line strings (if the builder should accept multiple source file extensions), a Python function; an Action object (see the next section); or a list of any of the above. An action function takes three arguments: .I source - a list of source nodes, .I target - a list of target nodes, .I env - the construction environment. .IP multi Specifies whether this builder is allowed to be called multiple times for the same target file(s). The default is 0, which means the builder can not be called multiple times for the same target file(s). Calling a builder multiple times for the same target simply adds additional source files to the target; it is not allowed to change the environment associated with the target, specify addition environment overrides, or associate a different builder with the target. .IP prefix The prefix that will be prepended to the target file name. .IP suffix The suffix that will be appended to the target file name. .IP src_suffix The expected source file name suffix. .IP src_builder Specifies a builder to use when a source file name suffix does not match any of the suffixes of the builder. Using this argument produces a multi-stage builder. .IP emitter A function that is passed the target, source, and environment, and which returns a tuple containing two lists, the list of targets to be built by this builder, and the list of sources for this builder. This allows the target and source lists to be manipulated before the target(s) are actually built. The emitter function takes three arguments: .I source - a list of source nodes, .I target - a list of target nodes, .I env - the construction environment. Example: .ES def e(target, source, env): return (target + ['foo.foo'], source + ['foo.src']) b = Builder(emitter=e) .EE .IP generator A function that returns a list of actions that will be executed to build the target(s) from the source(s). The returned action(s) may be an Action object, or anything that can be converted into an Action object (see the next section). The generator function takes four arguments: .I source - a list of source nodes, .I target - a list of target nodes, .I env - the construction environment. .I for_signature - a Boolean value that specifies whether the generator is being called for generating a build signature (as opposed to actually executing the command). Example: .ES def g(source, target, env, for_signature): return [["gcc", "-c", "-o"] + target + source] b = Builder(generator=g) .EE The .I generator and .I action arguments must not both be used for the same Builder. Any additional keyword arguments supplied when a Builder object is called will be associated with the target (and any other files built as a result of the call). .ES b = Builder(action="build < $SOURCE > $TARGET") env = Environment(BUILDERS = {'MyBuild' : b}) env.MyBuild('foo.out', 'foo.in', my_arg = 'xyzzy') .EE These extra keyword arguments are passed to the following functions: command generator functions, function Actions, and emitter functions. .SS Action Objects The Builder function will turn its .B action keyword argument into an appropriate internal Action object. Occasionally, it may be more efficient to create an explicit Action object and use it to initialize multiple Builder objects, rather than let each separate Builder object create a separate Action. The Action method takes a single argument and returns an appropriate object for the action represented by the type of the argument: .IP Action If the argument is already an Action object, the object is simply returned. .IP String If the argument is a string, a command-line Action is returned. .ES Action('$CC -c -o $TARGET $SOURCES') .EE .\" XXX From Gary Ruben, 23 April 2002: .\" What would be useful is a discussion of how you execute command .\" shell commands ie. what is the process used to spawn the shell, pass .\" environment variables to it etc., whether there is one shell per .\" environment or one per command etc. It might help to look at the Gnu .\" make documentation to see what they think is important to discuss about .\" a build system. I'm sure you can do a better job of organising the .\" documentation than they have :-) .IP List If the argument is a list, then a list of Action objects is returned. An Action object is created as necessary for each element in the list. If an element .I within the list is itself a list, the internal list is the command and arguments to be executed via the command line. This allows white space to be enclosed in an argument by defining a command in a list within a list: .ES Action([['cc', '-c', '-DWHITE SPACE', '-o', '$TARGET', '$SOURCES']]) .EE .IP Function If the argument is a Python function, a function Action is returned. The Python function takes three keyword arguments, .B target (a Node object representing the target file), .B source (a Node object representing the source file) and .BR env (the construction environment used for building the target file). The .B target and .B source arguments may be lists of Node objects if there is more than one target file or source file. The actual target and source file name(s) may be retrieved from their Node objects via the built-in Python str() function: .ES target_file_name = str(target) source_file_names = map(lambda x: str(x), source) .EE .IP The function should return .B 0 or .B None to indicate a successful build of the target file(s). The function may raise an exception or return a non-zero exit status to indicate an unsuccessful build. .ES def build_it(target = None, source = None, env = None): # build the target from the source return 0 a = Action(build_it) .EE .PP If the action argument is not one of the above, None is returned. .SS Variable Substitution Before executing a command, .B scons performs construction variable interpolation on the strings that make up the command line of builders. Variables are introduced by a .B $ prefix. Besides construction variables, scons provides the following variables for each command execution: .IP TARGET The file name of the target being built, or the file name of the first target if multiple targets are being built. .IP TARGETS The file names of all targets being built. .IP SOURCE The file name of the source of the build command, or the file name of the first source if multiple sources are being built. .IP SOURCES The file names of the sources of the build command. .LP For example, given the construction variable CC='cc', targets=['foo'], and sources=['foo.c', 'bar.c']: .ES action='$CC -c -o $TARGET $SOURCES' .EE would produce the command line: .ES cc -c -o foo foo.c bar.c .EE Variable names may be surrounded by curly braces ({}) to separate the name from the trailing characters. Within the curly braces, a variable name may have a Python slice subscript appended to select one or more items from a list. In the previous example, the string: .ES ${SOURCES[1]} .EE would produce: .ES bar.c .EE Additionally, a variable name may have the following special modifiers appended within the enclosing curly braces to modify the interpolated string: .IP base The base path of the file name, including the directory path but excluding any suffix. .IP dir The name of the directory in which the file exists. .IP file The file name, minus any directory portion. .IP filebase Just the basename of the file, minus any suffix and minus the directory. .IP suffix Just the file suffix. .IP abspath The absolute path name of the file. .LP For example, the specified target will expand as follows for the corresponding modifiers: .ES $TARGET => sub/dir/file.x ${TARGET.base} => sub/dir/file ${TARGET.dir} => sub/dir ${TARGET.file} => file.x ${TARGET.filebase} => file ${TARGET.suffix} => .x ${TARGET.abspath} => /top/dir/sub/dir/file.x .EE .LP The special pseudo-variables .R $( and .R $) may be used to surround parts of a command line that may change .I without causing a rebuild--that is, which are not included in the signature of target files built with this command. All text between .R $( and .R $) will be removed from the command line before it is added to file signatures, and the .R $( and .R $) will be removed before the command is executed. For example, the command line: .ES echo Last build occurred $( $TODAY $). > $TARGET .EE .LP would execute the command: .ES echo Last build occurred $TODAY. > $TARGET .EE .LP but the command signature added to any target files would be: .ES echo Last build occurred . > $TARGET .EE SCons uses the following rules when converting construction variables into command lines: .IP String When the value is a string it is interpreted as a space delimited list of command line arguments. .IP List When the value is a list it is interpreted as a list of command line arguments. Each element of the list is converted to a string. .IP Other Anything that is not a list or string is converted to a string and interpreted as a single command line argument. .IP Newline Newline characters (\\n) delimit lines. The newline parsing is done after all other parsing, so it is not possible for arguments (e.g. file names) to contain embedded newline characters. This limitation will likely go away in a future version of SCons. .SS Scanner Objects You can use the .B Scanner function to define objects to scan new file types for implicit dependencies. Scanner accepts the following arguments: .IP name The name of the Scanner. This is mainly used to identify the Scanner internally. .IP argument An optional argument that, if specified, will be passed to the scanner function. .IP skeys An optional list that can be used to determine which scanner should be used for a given Node. In the usual case of scanning for file names, this array can be a list of suffixes for the different file types that this Scanner knows how to scan. .IP function A Python function that will process the Node (file) and return a list of strings (file names) representing the implicit dependencies found in the contents. The function takes three or four arguments: def scanner_function(node, env, target): def scanner_function(node, env, target, arg): The .B node argument is the internal SCons node representing the file. Use .B str(node) to fetch the name of the file, and .B node.get_contents() to fetch contents of the file. The .B env argument is the construction environment for the scan. Fetch values from it using the .B env.Dictionary() method. The .B target argument is the internal SCons node representing the target file. The .B arg argument is the argument supplied when the scanner was created, if any. .IP scan_check An optional Python function that takes a Node (file) as an argument and returns whether the Node should, in fact, be scanned for dependencies. This check can be used to eliminate unnecessary calls to the scanner function when, for example, the underlying file represented by a Node does not yet exist. .SH SYSTEM-SPECIFIC BEHAVIOR SCons and its configuration files are very portable, due largely to its implementation in Python. There are, however, a few portability issues waiting to trap the unwary. .SS .C file suffix SCons handles the upper-case .B .C file suffix differently, depending on the capabilities of the underlying system. On a case-sensitive system such as Linux or UNIX, SCons treats a file with a .B .C suffix as a C++ source file. On a case-insensitive system such as Windows, SCons treats a file with a .B .C suffix as a C source file. .SS .F file suffix SCons handles the upper-case .B .F file suffix differently, depending on the capabilities of the underlying system. On a case-sensitive system such as Linux or UNIX, SCons treats a file with a .B .F suffix as a Fortran source file that is to be first run through the standard C preprocessor. On a case-insensitive system such as Windows, SCons treats a file with a .B .F suffix as a Fortran source file that should .I not be run through the C preprocessor. .SS WIN32: Cygwin Tools and Cygwin Python vs. Windows Pythons Cygwin supplies a set of tools and utilities that let users work on a Windows system using a more POSIX-like environment. The Cygwin tools, including Cygwin Python, do this, in part, by sharing an ability to interpret UNIX-like path names. For example, the Cygwin tools will internally translate a Cygwin path name like /cygdrive/c/mydir to an equivalent Windows pathname of C:/mydir (equivalent to C:\\mydir). Versions of Python that are built for native Windows execution, such as the python.org and ActiveState versions, do not have the Cygwin path name semantics. This means that using a native Windows version of Python to build compiled programs using Cygwin tools (such as gcc, bison, and flex) may yield unpredictable results. "Mixing and matching" in this way can be made to work, but it requires careful attention to the use of path names in your SConscript files. In practice, users can sidestep the issue by adopting the following rules: When using gcc, use the Cygwin-supplied Python interpreter to run SCons; when using Microsoft Visual C/C++ (or some other Windows compiler) use the python.org or ActiveState version of Python to run SCons. .SS WIN32: scons.bat file On WIN32 systems, SCons is executed via a wrapper .B scons.bat file. This has (at least) two ramifications: First, Windows command-line users that want to use variable assignment on the command line may have to put double quotes around the assignments: .ES scons "FOO=BAR" "BAZ=BLEH" .EE Second, the Cygwin shell does not recognize this file as being the same as an .B scons command issued at the command-line prompt. You can work around this either by executing .B scons.bat from the Cygwin command line, or by creating a wrapper shell script named .B scons . .SH EXAMPLES To help you get started using SCons, this section contains a brief overview of some common tasks. NOTE: SCons does .I not build all of its targets by default, like other build tools do. The canonical way to invoke SCons is with a target of '.' (dot) to represent all targets in and below the current directory: .ES scons . .EE One or more default targets may be specified via the Default() method in the SConstruct file. .SS Basic Compilation From a Single Source File .ES env = Environment() env.Program(target = 'foo', source = 'foo.c') .EE Note: Build the file by specifying the target as an argument ("scons foo" or "scons foo.exe"). or by specifying a dot ("scons ."). .SS Basic Compilation From Multiple Source Files .ES env = Environment() env.Program(target = 'foo', source = 'f1.c f2.c f3.c') .EE .SS Setting a Compilation Flag .ES env = Environment(CCFLAGS = '-g') env.Program(target = 'foo', source = 'foo.c') .EE .SS Search The Local Directory For .h Files Note: You do .I not need to set CCFLAGS to specify -I options by hand. SCons will construct the right -I options from CPPPATH. .ES env = Environment(CPPPATH = ['.']) env.Program(target = 'foo', source = 'foo.c') .EE .SS Search Multiple Directories For .h Files .ES env = Environment(CPPPATH = ['include1', 'include2']) env.Program(target = 'foo', source = 'foo.c') .EE .SS Building a Static Library .ES env = Environment() env.StaticLibrary(target = 'foo', source = 'l1.c l2.c') .EE .SS Building a Shared Library .ES env = Environment() env.SharedLibrary(target = 'foo', source = 'l3.c l4.c') .EE .SS Linking a Local Library Into a Program .ES env = Environment(LIBS = 'mylib', LIBPATH = ['.']) env.Library(target = 'mylib', source = 'l1.c l2.c') env.Program(target = 'prog', source = 'p1.c p2.c') .EE .SS Defining Your Own Builder Object Notice that when you invoke the Builder, you can leave off the target file suffix, and SCons will add it automatically. .ES bld = Builder(action = 'pdftex < $SOURCES > $TARGET' suffix = '.pdf', src_suffix = '.tex') env = Environment(BUILDERS = {'PDFBuilder' : bld}) env.PDFBuilder(target = 'foo.pdf', source = 'foo.tex') # The following creates "bar.pdf" from "bar.tex" env.PDFBuilder(target = 'bar', source = 'bar') .EE .SS Defining Your Own Scanner Object .ES import re include_re = re.compile(r'^include\\s+(\\S+)$', re.M) def kfile_scan(node, env, target, arg): contents = node.get_contents() includes = include_re.findall(contents) return includes kscan = Scanner(name = 'kfile', function = kfile_scan, argument = None, skeys = ['.k']) scanners = Environment().Dictionary('SCANNERS') env = Environment(SCANNERS = scanners + [kscan]) env.Command('foo', 'foo.k', 'kprocess < $SOURCES > $TARGET') bar_in = File('bar.in') env.Command('bar', bar_in, 'kprocess $SOURCES > $TARGET') bar_in.target_scanner = kscan .EE .SS Creating a Hierarchical Build Notice that the file names specified in a subdirectory's SConscript file are relative to that subdirectory. .ES SConstruct: env = Environment() env.Program(target = 'foo', source = 'foo.c') SConscript('sub/SConscript') sub/SConscript: env = Environment() # Builds sub/foo from sub/foo.c env.Program(target = 'foo', source = 'foo.c') SConscript('dir/SConscript') sub/dir/SConscript: env = Environment() # Builds sub/dir/foo from sub/dir/foo.c env.Program(target = 'foo', source = 'foo.c') .EE .SS Sharing Variables Between SConscript Files You must explicitly Export() and Import() variables that you want to share between SConscript files. .ES SConstruct: env = Environment() env.Program(target = 'foo', source = 'foo.c') Export("env") SConscript('subdirectory/SConscript') subdirectory/SConscript: Import("env") env.Program(target = 'foo', source = 'foo.c') .EE .SS Building Multiple Variants From the Same Source Use the BuildDir() method to establish one or more separate build directories for a given source directory, then use the SConscript() method to specify the SConscript files in the build directories: .ES SConstruct: ccflags = '-DFOO' Export("ccflags") BuildDir('foo', 'src') SConscript('foo/SConscript') ccflags = '-DBAR' Export("ccflags") BuildDir('bar', 'src') SConscript('bar/SConscript') src/SConscript: Import("ccflags") env = Environment(CCFLAGS = ccflags) env.Program(target = 'src', source = 'src.c') .EE Note the use of the Export() method to set the "ccflags" variable to a different value for each variant build. .SS Hierarchical Build of Two Libraries Linked With a Program .ES SConstruct: env = Environment(LIBPATH = ['#libA', '#libB']) Export('env') SConscript('libA/SConscript') SConscript('libB/SConscript') SConscript('Main/SConscript') libA/SConscript: Import('env') env.Library('a', 'a1.c a2.c a3.c') libB/SConscript: Import('env') env.Library('b', 'b1.c b2.c b3.c') Main/SConscript: Import('env') e = env.Copy(LIBS = ['a', ','b']) e.Program('foo', 'm1.c m2.c m3.c') .EE The '#' in the LIBPATH directories specify that they're relative to the top-level directory, so they don't turn into "Main/libA" when they're used in Main/SConscript. Specifying only 'a' and 'b' for the library names allows SCons to append the appropriate library prefix and suffix for the current platform (for example, 'liba.a' on POSIX systems, 'a.lib' on Windows). .SS Customizing contruction variables from the command line. The following would allow the C compiler to be specified on the command line or in the file custom.py. .ES opts = Options('custom.py') opts.Add('CC', 'The C compiler.') env = Environment(options=opts) Help(opts.GenerateHelpText(env)) .EE The user could specify the C compiler on the command line: .ES scons "CC=my_cc" .EE or in the custom.py file: .ES CC = 'my_cc' .EE or get documentation on the options: .ES > scons -h CC: The C compiler. default: None actual: cc .EE .SS Using Microsoft Visual C++ precompiled headers Since windows.h includes everything and the kitchen sink, it can take quite some time to compile it over and over again for a bunch of object files, so Microsoft provides a mechanism to compile a set of headers once and then include the previously compiled headers in any object file. This technology is called precompiled headers. The general recipe is to create a file named "StdAfx.cpp" that includes a single header named "StdAfx.h", and then include every header you want to precompile in "StdAfx.h", and finally include "StdAfx.h" as the first header in all the source files you are compiling to object files. For example: StdAfx.h: .ES #include #include .EE StdAfx.cpp: .ES #include .EE Foo.cpp: .ES #include /* do some stuff */ .EE Bar.cpp: .ES #include /* do some other stuff */ .EE SConstruct: .ES env=Environment() env['PCHSTOP'] = StdAfx.h env['PCH'] = env.PCH('StdAfx.cpp')[0] env.Program('MyApp', ['Foo.cpp', 'Bar.cpp']) .EE For more information see the document for the PCH builder, and the PCH and PCHSTOP construction variables. To learn about the details of precompiled headers consult the MSDN documention for /Yc, /Yu, and /Yp. .SS Using Microsoft Visual C++ external debugging information Since including debugging information in programs and shared libraries can cause their size to increase significantly, Microsoft provides a mechanism for including the debugging information in an external file called a PDB file. SCons supports PDB files through the PDB construction variable. SConstruct: .ES env=Environment() env['PDB'] = 'MyApp.pdb' env.Program('MyApp', ['Foo.cpp', 'Bar.cpp']) .EE For more information see the document for the PDB construction variable. .SH ENVIRONMENT .IP SCONS_LIB_DIR Specifies the directory that contains the SCons Python module directory (e.g. /home/aroach/scons-src-0.01/src/engine). .IP SCONSFLAGS A string of options that will be used by scons in addition to those passed on the command line. .SH "SEE ALSO" .B scons User Manual, .B scons Design Document, .B scons source code. .SH AUTHORS Steven Knight .br Anthony Roach