2 # __FILE__ __REVISION__ __DATE__ __DEVELOPER__
5 SCons - a software construction tool
10 This is a beta release of SCons, a tool for building software (and other
11 files). SCons is implemented in Python, and its "configuration files"
12 are actually Python scripts, allowing you to use the full power of a
13 real scripting language to solve build problems. You do not, however,
14 need to know Python to use SCons effectively.
16 So that everyone using SCons can help each other learn how to use it
17 more effectively, please sign up for the scons-users mailing list at:
19 http://lists.sourceforge.net/lists/listinfo/scons-users
25 This is a pre-release for testing the eighth beta release of SCons.
26 Please consult the CHANGES.txt file for a list of specific changes
29 Please note the following important changes since release 0.96:
31 -- DIRECTORY TREES ARE NO LONGER AUTOMATICALLY SCANNED FOR CHANGES
33 Custom builders and Command() calls that accept directories as
34 source arguments no longer scan entire on-disk directory trees
35 by default. This means that their targets will not be
36 automatically rebuilt if a file changes on disk, and SCons does
37 *not* already know about. Note that the targets will still be
38 rebuilt correctly if a file changes that SCons already knows
39 about due to a Builder or other call.
41 The existing behavior of scanning on-disk directory trees for
42 any changed file can be maintained by passing the new DirScanner
43 global directory scanner as the source_scanner keyword argument
46 bld = Builder("build < $SOURCE > $TARGET",
47 source_scanner = DirScanner)
49 The same keyword argument can also be supplied to any Command()
50 calls that need to scan directory trees on-disk for changed files:
52 env.Command("archive.out", "directory",
53 "archiver -o $TARGET $SOURCE",
54 source_scanner = DirScanner)
56 This change was made because scanning directories by default
57 could cause huge slowdowns if a configurable directory like /usr
58 or /usr/local was passed as the source to a Builder or Command()
59 call, in which case SCons would scan the entire directory tree.
61 -- SIGNATURES ARE NOW STORED IN AN SConsignFile() BY DEFAULT,
62 CAUSING LIKELY REBUILDS; SPECIAL NOTE CONCERNING INTERACTION
65 The default behavior has been changed to store signature
66 information in a single .sconsign.dblite file in the top-level
67 SConstruct file. This will cause rebuilds on upgrade to 0.97,
68 unless you were already calling the SConsignFile() function in
69 your SConscript files.
71 The previous default behavior was to store signature information
72 in a .sconsign file in each directory that contained target
73 files that SCons knew about. The old behavior may be preserved
78 in any SConscript file.
80 If you are using the Repository feature, are not already using
81 the SConsignFile() function in your build, you *must* add
82 SConsignFile(None) to your build to keep interoperating with an
83 existing Repository that uses the old behavior of a .sconsign
84 file in each directory. Alternatively, you can rebuild the
85 Repository with the new default behavior.
87 -- OTHER SIGNATURE CHANGES WILL CAUSE LIKELY REBUILDS AFTER UPGRADE
89 This release adds several changes to the signature mechanism that
90 will cause SCons to rebuild most configurations after upgrading
91 (and when switching back to an earlier release from 0.97).
94 -- NORMALIZED PATHS IN SConsignFile() DATABASES ON WINDOWS
96 When using an SConsignFile() database, instead of individual
97 .sconsign files in each directory, the path names are
98 stored in normalized form with / (forward slash) separating
99 the elements. This may cause rebuilds on Windows systems
100 with hierarchical configurations.
102 -- STORED DEPENDENCY PATHS ARE NOW RELATIVE TO THE TARGET
104 SCons used to store the paths of all source files and
105 dependencies relative to the top-level SConstruct directory.
106 It now stores them relative to the directory of the
107 associated target file. This makes it possible to use
108 content signatures to subdivide a dependency tree without
109 causing unnecessary rebuilds due to an intermediate file in
110 one build being treated as a source file in a nother build.
112 This a step towards making it possible to write a hierarchy
113 of SConstruct files that allow developers to build just
114 one portion of a tree wherever there's an SConstruct file.
115 (Note that this would still require some specific code at
116 the top of each SConstruct file, but we hope to make this
117 an easier/more naturally supported thing in the future.)
119 -- PYTHON FUNCTION ACTION SIGNATURES HAVE CHANGED TO AVOID
120 FUTURE REBUILDS AND REBUILDS BETWEEN PYTHON VERSIONS
122 SCons Actions for Python functions use the functions byte
123 code to generate their signature. The byte code in older
124 versions of Python includes indications of the line numbers
125 at which the function's code appeared in its original
126 source file, which means that changes in the location of
127 an otherwise unmodified Python function would trigger
128 rebuilds. The line number byte codes are now removed
129 from the signature, which will cause any targets built by
130 Python function Actions (including various pre-supplied
131 SCons Actions) be rebuilt.
133 -- REMOVED CONVERSION FROM PRE-0.96 .sconsign FORMATS
135 Because this release involves so many other signature
136 changes that cause rebuilds, the support for automatically
137 converting signature information from .sconsign files
138 written by SCons versions prior to 0.96 has been removed.
140 -- ORDER OF -o FLAGS ON CERTAIN LINK COMMAND LINES HAS CHANGED
142 The -o flag that specifies an output file has been moved on
143 certain linker command lines to place it consistently after
144 the link command itself. This will cause recompilation
145 of target files created by these changed lines.
147 -- F95 AND F90 COMPILERS ARE NOW PREFERRED OVER F77
149 SCons now searches for Fortran 95 and Fortran 90 compilers first
150 in preference to Fortran 77. This may result in a different
151 Fortran compiler being used by default, although as Fortran 95 and
152 Fortran 90 are backwards compatible with Fortran 77, this should
153 not cause problems for standards-compliant Fortran programs.
154 On systems that have multiple versions of Fortran installed,
155 the Fortran 77 compiler may be explicitly selected by specifying
156 it when creating the construction environment:
158 env = Environment(tools = ['default', 'f77'])
160 -- SOLARIS DEFAULT SHARED OBJECT PREFIXES AND SUFFIXES HAVE CHANGED
162 On Solaris, SCons now builds shared objects from C and C++ source
163 files with a default prefix of "so_" and a default suffix of ".o".
164 The previous default suffix of ".os" caused problems when trying
165 to use SCons with Sun WorkShop.
167 -- CACHED Configure() RESULTS ARE STORED IN A DIFFERENT FILE
169 The Configure() subsystem now stores its cached results in a
170 different file. This may cause configuration tests to be re-run
171 the first time after you install 0.97.
173 -- setup.py INSTALLS VERSION-NUMBERED SCRIPTS AND DIRS BY DEFAULT
175 The setup.py script has been changed to always install SCons in
176 a version-numbered directory (e.g. /usr/local/lib/scons-0.97
177 or D:\Python23\scons-0.97) and with a version-numbered script
178 name (scons-0.97) in addition to the usual installation of an
179 "scons" script name. A number of new setup.py options allow
180 control over what does or does not get installed, and where.
181 See the README.txt or README files for additional information.
183 -- setup.py NOW INSTALLS MAN PAGES ON UNIX AND Linux SYSTEMS
185 The SCons setup.py script now installs the "scons.1" and
186 "sconsign.1" man pages on UNIX and Linux systems. A
189 -- ParseConfig() METHOD ADDS LIBRARY FILE NAMES TO THE $LIBS VARIABLE
191 The ParseConfig() method now adds library file names returned
192 by the specified *-config command to the $LIBS construction
193 variable, instead of returning them (the same way it handles
196 -- ParseConfig() METHOD DOESN'T ADD DUPLICATES TO CONSTRUCTION VARIABLES
198 By default, the ParseConfig() method now avoids adding duplicate
199 entries to construction variables. The old behavior may be
200 specified using a new "unique=0" keyword argument.
202 -- WINDOWS %TEMP% and %TMP% VARIABLES ARE PROPAGATED AUTOMATICALLY
204 The %TEMP% and %TMP% external environment variables are now
205 propagated automatically to the command execution environment on
208 -- VISUAL STUDIO ATL AND MFC DIRECTORIES NOT ADDED BY DEFAULT
210 When compiling with Microsoft Visual Studio, SCons no longer
211 adds the ATL and MFC directories to the INCLUDE and LIB
212 environment variables by default. If you want these directories
213 included in your environment variables, you should now set the
214 $MSVS_USE_MFC_DIRS *construction* variable when initializing
217 env = Environment(MSVS_USE_MFC_DIRS = 1)
219 -- BUILDERS RETURN A LIST-LIKE OBJECT, NOT A REGULAR LIST
221 Builders calls now return an object that behaves like a list
222 (and which provides some other functionality), not an underlying
223 Python list. In general, this should not cause any problems,
224 although it introduces a subtle change in the following behavior:
226 obj += env.Object('foo.c')
228 If "obj" is a list, Python will no longer update the "obj" in
229 place, because the return value from env.Object() is no longer
230 the same type. Python will instead allocate a new object and
231 assign the local variable "obj" to it. If "obj" is defined in
232 an SConscript file that calls another SConscript file containing
233 the above code, "obj" in the first SConscript file will not
236 You can guarantee that a list will be updated in place regardless
237 of which SConscript file defines it and which adds to it by
238 using the list append() method as follows:
240 obj.append(env.Object('foo.c'))
242 -- OUTPUT OF Configure() SUBSYSTEM CHANGED SLIGHTLY
244 The Configure() subsystem now reports tests results as "yes" and
245 "no" instead of "ok" and "failed." This might interfere with any
246 scripts that automatically parse the Configure() output from SCons.
248 -- DEPRECATED GLOBAL FUNCTIONS HAVE BEEN REMOVED
250 The following deprecated global functions have been removed:
251 ParseConfig(), SetBuildSignatureType(), SetContentSignatureType(),
252 SetJobs() and GetJobs().
254 -- DEPRECATED "validater" KEYWORD HAS BEEN REMOVED
256 The deprecated "validater" keyword to the Options.Add() method
259 Please note the following important changes since release 0.95:
261 -- BUILDERS NOW ALWAYS RETURN A LIST OF TARGETS
263 All Builder calls (both built-in like Program(), Library(),
264 etc. and customer Builders) now always return a list of target
265 Nodes. If the Builder only builds one target, the Builder
266 call will now return a list containing that target Node, not
267 the target Node itself as it used to do.
269 This change should be invisibile to most normal uses of the
270 return values from Builder calls. It will cause an error if the
271 SConscript file was performing some direct manipulation of the
272 returned Node value. For example, an attempt to print the name
273 of a target returned by the Object() Builder:
275 target = Object('foo.c')
279 Will now need to access the first element in the list returned by
282 target = Object('foo.c')
286 This change was introduced to make the data type returned by Builder
287 calls consistent (always a list), regardless of platform or number
290 -- DEFAULT SConsignFile() DATABASE SCHEME HAS CHANGED
292 The SConsignFile() function now uses an internally-supplied
293 SCons.dblite module as the default DB scheme for the .sconsign file.
294 If you are using the SConsignFile() function without an explicitly
295 specified dbm_module argument, this will cause all of your targets
296 to be recompiled the first time you use SCons 0.96. To preserve the
297 previous behavior, specify the "anydbm" module explicitly:
300 SConsignFile('.sconsign_file_name', anydbm)
302 -- INTERNAL .sconsign FILE FORMAT HAS CHANGED
304 The internal format of .sconsign files has been changed. This might
305 cause warnings about "ignoring corrupt .sconsign files" and rebuilds
306 when you use SCons 0.96 for the first time in a tree that was
307 previously built with SCons 0.95 or earlier.
309 -- INTERFACE CHANGE OF scan_check FUNCTION TO CUSTOM SCANNERS
311 The scan_check function that can be supplied to a custom Scanner now
312 must take two arguments, the Node to be checked and a construction
313 environment. It previously only used the Node as an argument.
315 -- DEFAULT SCANNERS NO LONGER HEED INTERNAL Scanner.add_skey() METHOD
317 The internal Scanner.add_skey() method no longer works for the
318 default scanners, which now use construction variables to hold their
319 lists of suffixes. If you had a custom Tool specification that was
320 reaching into the internals in this way to add a suffix to one of
321 the following scanner, you must now add the suffix to a construction
322 environment through which you plan to call the scanner, as follows:
324 CScan.add_skey('.x') => env.Append(CPPSUFFIXES = ['.x'])
325 DScan.add_skey('.x') => env.Append(DSUFFIXES = ['.x'])
326 FortranScan.add_skey('.x') => env.Append(FORTRANSUFFIXES = ['.x'])
328 -- KEYWORD ARGUMENTS TO Builder() HAVE BEEN REMOVED
330 The "node_factory" and "scanner" keyword arguments to the Builder()
331 function have been removed. In their place, the separate and more
332 flexible "target_factory," "source_factory," "target_scanner" and
333 "source scanner" keywords should be used instead.
335 -- ALL-DIGIT FILE "EXTENSIONS" ARE NOW PART OF THE FILE BASENAME
337 SCons now treats file "extensions" that contain all digits (for
338 example, "file.123") as part of the file basename, for easier
339 handling of version numbers in the names of shared libraries
340 and other files. Builders will now add their file extensions to
341 file names specified with all-digit extensions. If you need to
342 generate a file with an all-digit extension using a Builder that
343 adds a file extension, you can preserve the previous behavior by
344 wrapping the file name in a File() call.
346 -- Append()/Prepend() METHODS CHANGED WHEN USING UserList OBJECTS
348 The behavior of the env.Append() and env.Prepend() methods has
349 changed when appending a string value to a UserList, or vice versa.
350 They now behave like normal Python addition of a string to
351 a UserList. Given an initialization and an env.Append() call like:
353 env = Environment(VAR1=UserList(['foo']), VAR2='foo')
354 env.Append(VAR1='bar', VAR2=UserList(['bar'])
356 The resulting values of $VAR1 and $VAR2 will now be ['foo', 'b',
357 'a', 'r'] and ['f', 'o', 'o', 'bar'], respectively. This is because
358 Python UserList objects treat strings as sequences of letters when
359 adding them to the value of the UserList.
361 The old behavior of yielding $VAR1 and $VAR2 values of ['foo',
362 'bar'] when either variable is a UserList object now requires that
363 the string variables be enclosed in a list:
365 env = Environment(VAR1=UserList(['foo']), VAR2=['foo'])
366 env.Append(VAR1='bar', VAR2=UserList(['bar']))
368 Note that the SCons behavior when appending to normal lists has
369 *not* changed, and the behavior of all of the default values that
370 SCons uses to initialize all construction variables has *not*
371 changed. This change *only* affects any cases where you explicitly
372 use UserList objects to initialize or append to a variable.
374 Please note the following planned, future changes:
376 -- SCANNER NAMES HAVE BEEN DEPRECATED AND WILL BE REMOVED
378 Several internal variable names in SCons.Defaults for various
379 pre-made default Scanner objects have been deprecated and will
380 be removed in a future revision. In their place are several new
381 global variable names that are now part of the publicly-supported
384 NEW NAME DEPRECATED NAME
385 -------- ----------------------------
386 CScanner SCons.Defaults.CScan
387 DSCanner SCons.Defaults.DScan
388 SourceFileScanner SCons.Defaults.ObjSourceScan
389 ProgramScanner SCons.Defaults.ProgScan
391 Of these, only ObjSourceScan was probably used at all, to add
392 new mappings of file suffixes to other scanners for use by the
393 Object() Builder. This should now be done as follows:
395 SourceFileScanner.add_scanner('.x', XScanner)
397 SCons is developed with an extensive regression test suite, and a
398 rigorous development methodology for continually improving that suite.
399 Because of this, SCons is of sufficient quality that you can use it
400 for real work. The "beta" status of the release reflects that we
401 still may change interfaces in future releases, which may require
402 modifications to your SConscript files. We strive to hold these
403 changes to a minimum.
405 Nevertheless, please heed the following disclaimers:
407 - Please report any bugs or other problems that you find to our bug
408 tracker at our SourceForge project page:
410 http://sourceforge.net/tracker/?func=add&group_id=30337&atid=398971
412 We have a reliable bug-fixing methodology already in place and
413 strive to respond to problems relatively quickly.
415 - Documentation is spottier than we'd like. You may need to dive
416 into the source code to figure out how to do something. Asking
417 questions on the scons-users mailing list is also welcome. We
418 will be addressing the documentation in upcoming releases, but
419 would be more than glad to have your assistance in correcting this
422 In particular, the "SCons Design" documentation on the SCons web
423 site is currently out of date, as we made significant changes to
424 portions of the interface as we figured out what worked and what
425 didn't during implementation.
427 - There may be performance issues. Improving SCons performance
428 is an ongoing priority. If you still find the performance
429 unacceptable, we would very much like to hear from you and learn
430 more about your configuration so we can optimize the right things.
432 - Error messages don't always exist where they'd be helpful.
433 Please let us know about any errors you ran into that would
434 have benefitted from a (more) descriptive message.
436 KNOWN PROBLEMS IN THIS RELEASE:
438 For a complete list of known problems, consult the SCons bug tracker
441 http://sourceforge.net/tracker/?atid=398971&group_id=30337&func=browse
443 - Support for parallel builds (-j) does not work on WIN32 systems
444 prior to *official* Python release 2.2 (not 2.2 pre-releases).
446 Prior to Python 2.2, there is a bug in Python's Win32
447 implementation such that when a thread spawns an external command,
448 it blocks all threads from running. This breaks the SCons
449 multithreading architecture used to support -j builds.
451 We have included a patch file, os_spawnv_fix.diff, that you can
452 use if you you want to fix your version of Python to support
453 parallel builds in SCons.
455 - Again, the "SCons Design" documentation on the SCons web
456 site is currently out of date. Take what you read there with a
459 - On Win32 systems, you must put a space between the redirection
460 characters < and >, and the specified files (or construction
461 variable expansions):
463 command < $SOURCE > $TARGET
465 If you don't supply a space (for example, "<$SOURCE"), SCons will
466 not recognize the redirection.
468 - MSVC .res files are not rebuilt when icons change.
470 - The -c option does not clean up .sconsign files or directories
471 created as part of the build, and also does not clean up
472 SideEffect files (for example, Visual Studio .pdb files).
474 - Switching content signatures from "MD5" to "timestamp" and back
475 again can cause unusual errors. These errors can be cleared up by
476 removing all .sconsign files.
478 - When using multiple Repositories, changing the name of an include
479 file can cause an old version of the file to be used.
481 - There is currently no way to force use of a relative path (../*)
482 for directories outside the top-level SConstruct file.
484 - The Jar() Builder will, on its second or subsequent invocation,
485 package up the .sconsign files that SCons uses to track signatures.
486 You can work around this by using the SConsignFile() function
487 to collect all of the .sconsign information into a single file
488 outside of the directory being packaged by Jar().
490 - SCons does not currently have a way to detect that an intermediate
491 file has been corrupted from outside and should be rebuilt.
493 - Unicode characters in path names do not work in all circumstances.
495 - A stray source file in a BuildDir can prevent targets from being
496 (re)built when they should.
498 - SCons does not automatically rebuild LaTeX files when the file
499 has an undefined reference on the first build.
501 - Use of --implicit-cache with TargetSignatures('content') can,
502 for some changes, not rebuild a file when necessary.
504 - SCons does not currently automatically check out SConstruct or
505 SConscript files from SCCS, RCS or BitKeeper.
507 - No support yet for the following planned command-line options:
509 -d -e -l --list-actions --list-derived --list-where
510 -o --override -p -r -R -w --write-filenames
511 -W --warn-undefined-variables
515 Thank you for your interest, and please let us know how we can help
516 improve SCons for your needs.
519 knight at baldmt dot com
520 http://www.baldmt.com/~knight/
522 With plenty of help from the SCons Development team: