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 -- INTERNAL FUNCTIONS AND CLASSES HAVE MOVED FROM SCons.Util
261 All internal functions and classes related to string substitution
262 have been moved out of the SCons.Util module into their own
263 SCons.Subst module. The following classes have been moved:
271 And the following functions have moved:
280 If your SConscript files have been using any of these function
281 directly from the SCons.Util module (which they ultimately should
282 not be!), you will need to modify them.
284 Please note the following important changes since release 0.95:
286 -- BUILDERS NOW ALWAYS RETURN A LIST OF TARGETS
288 All Builder calls (both built-in like Program(), Library(),
289 etc. and customer Builders) now always return a list of target
290 Nodes. If the Builder only builds one target, the Builder
291 call will now return a list containing that target Node, not
292 the target Node itself as it used to do.
294 This change should be invisibile to most normal uses of the
295 return values from Builder calls. It will cause an error if the
296 SConscript file was performing some direct manipulation of the
297 returned Node value. For example, an attempt to print the name
298 of a target returned by the Object() Builder:
300 target = Object('foo.c')
304 Will now need to access the first element in the list returned by
307 target = Object('foo.c')
311 This change was introduced to make the data type returned by Builder
312 calls consistent (always a list), regardless of platform or number
315 -- DEFAULT SConsignFile() DATABASE SCHEME HAS CHANGED
317 The SConsignFile() function now uses an internally-supplied
318 SCons.dblite module as the default DB scheme for the .sconsign file.
319 If you are using the SConsignFile() function without an explicitly
320 specified dbm_module argument, this will cause all of your targets
321 to be recompiled the first time you use SCons 0.96. To preserve the
322 previous behavior, specify the "anydbm" module explicitly:
325 SConsignFile('.sconsign_file_name', anydbm)
327 -- INTERNAL .sconsign FILE FORMAT HAS CHANGED
329 The internal format of .sconsign files has been changed. This might
330 cause warnings about "ignoring corrupt .sconsign files" and rebuilds
331 when you use SCons 0.96 for the first time in a tree that was
332 previously built with SCons 0.95 or earlier.
334 -- INTERFACE CHANGE OF scan_check FUNCTION TO CUSTOM SCANNERS
336 The scan_check function that can be supplied to a custom Scanner now
337 must take two arguments, the Node to be checked and a construction
338 environment. It previously only used the Node as an argument.
340 -- DEFAULT SCANNERS NO LONGER HEED INTERNAL Scanner.add_skey() METHOD
342 The internal Scanner.add_skey() method no longer works for the
343 default scanners, which now use construction variables to hold their
344 lists of suffixes. If you had a custom Tool specification that was
345 reaching into the internals in this way to add a suffix to one of
346 the following scanner, you must now add the suffix to a construction
347 environment through which you plan to call the scanner, as follows:
349 CScan.add_skey('.x') => env.Append(CPPSUFFIXES = ['.x'])
350 DScan.add_skey('.x') => env.Append(DSUFFIXES = ['.x'])
351 FortranScan.add_skey('.x') => env.Append(FORTRANSUFFIXES = ['.x'])
353 -- KEYWORD ARGUMENTS TO Builder() HAVE BEEN REMOVED
355 The "node_factory" and "scanner" keyword arguments to the Builder()
356 function have been removed. In their place, the separate and more
357 flexible "target_factory," "source_factory," "target_scanner" and
358 "source scanner" keywords should be used instead.
360 -- ALL-DIGIT FILE "EXTENSIONS" ARE NOW PART OF THE FILE BASENAME
362 SCons now treats file "extensions" that contain all digits (for
363 example, "file.123") as part of the file basename, for easier
364 handling of version numbers in the names of shared libraries
365 and other files. Builders will now add their file extensions to
366 file names specified with all-digit extensions. If you need to
367 generate a file with an all-digit extension using a Builder that
368 adds a file extension, you can preserve the previous behavior by
369 wrapping the file name in a File() call.
371 -- Append()/Prepend() METHODS CHANGED WHEN USING UserList OBJECTS
373 The behavior of the env.Append() and env.Prepend() methods has
374 changed when appending a string value to a UserList, or vice versa.
375 They now behave like normal Python addition of a string to
376 a UserList. Given an initialization and an env.Append() call like:
378 env = Environment(VAR1=UserList(['foo']), VAR2='foo')
379 env.Append(VAR1='bar', VAR2=UserList(['bar'])
381 The resulting values of $VAR1 and $VAR2 will now be ['foo', 'b',
382 'a', 'r'] and ['f', 'o', 'o', 'bar'], respectively. This is because
383 Python UserList objects treat strings as sequences of letters when
384 adding them to the value of the UserList.
386 The old behavior of yielding $VAR1 and $VAR2 values of ['foo',
387 'bar'] when either variable is a UserList object now requires that
388 the string variables be enclosed in a list:
390 env = Environment(VAR1=UserList(['foo']), VAR2=['foo'])
391 env.Append(VAR1='bar', VAR2=UserList(['bar']))
393 Note that the SCons behavior when appending to normal lists has
394 *not* changed, and the behavior of all of the default values that
395 SCons uses to initialize all construction variables has *not*
396 changed. This change *only* affects any cases where you explicitly
397 use UserList objects to initialize or append to a variable.
399 Please note the following planned, future changes:
401 -- SCANNER NAMES HAVE BEEN DEPRECATED AND WILL BE REMOVED
403 Several internal variable names in SCons.Defaults for various
404 pre-made default Scanner objects have been deprecated and will
405 be removed in a future revision. In their place are several new
406 global variable names that are now part of the publicly-supported
409 NEW NAME DEPRECATED NAME
410 -------- ----------------------------
411 CScanner SCons.Defaults.CScan
412 DSCanner SCons.Defaults.DScan
413 SourceFileScanner SCons.Defaults.ObjSourceScan
414 ProgramScanner SCons.Defaults.ProgScan
416 Of these, only ObjSourceScan was probably used at all, to add
417 new mappings of file suffixes to other scanners for use by the
418 Object() Builder. This should now be done as follows:
420 SourceFileScanner.add_scanner('.x', XScanner)
422 SCons is developed with an extensive regression test suite, and a
423 rigorous development methodology for continually improving that suite.
424 Because of this, SCons is of sufficient quality that you can use it
425 for real work. The "beta" status of the release reflects that we
426 still may change interfaces in future releases, which may require
427 modifications to your SConscript files. We strive to hold these
428 changes to a minimum.
430 Nevertheless, please heed the following disclaimers:
432 - Please report any bugs or other problems that you find to our bug
433 tracker at our SourceForge project page:
435 http://sourceforge.net/tracker/?func=add&group_id=30337&atid=398971
437 We have a reliable bug-fixing methodology already in place and
438 strive to respond to problems relatively quickly.
440 - Documentation is spottier than we'd like. You may need to dive
441 into the source code to figure out how to do something. Asking
442 questions on the scons-users mailing list is also welcome. We
443 will be addressing the documentation in upcoming releases, but
444 would be more than glad to have your assistance in correcting this
447 In particular, the "SCons Design" documentation on the SCons web
448 site is currently out of date, as we made significant changes to
449 portions of the interface as we figured out what worked and what
450 didn't during implementation.
452 - There may be performance issues. Improving SCons performance
453 is an ongoing priority. If you still find the performance
454 unacceptable, we would very much like to hear from you and learn
455 more about your configuration so we can optimize the right things.
457 - Error messages don't always exist where they'd be helpful.
458 Please let us know about any errors you ran into that would
459 have benefitted from a (more) descriptive message.
461 KNOWN PROBLEMS IN THIS RELEASE:
463 For a complete list of known problems, consult the SCons bug tracker
466 http://sourceforge.net/tracker/?atid=398971&group_id=30337&func=browse
468 - Support for parallel builds (-j) does not work on WIN32 systems
469 prior to *official* Python release 2.2 (not 2.2 pre-releases).
471 Prior to Python 2.2, there is a bug in Python's Win32
472 implementation such that when a thread spawns an external command,
473 it blocks all threads from running. This breaks the SCons
474 multithreading architecture used to support -j builds.
476 We have included a patch file, os_spawnv_fix.diff, that you can
477 use if you you want to fix your version of Python to support
478 parallel builds in SCons.
480 - Again, the "SCons Design" documentation on the SCons web
481 site is currently out of date. Take what you read there with a
484 - On Win32 systems, you must put a space between the redirection
485 characters < and >, and the specified files (or construction
486 variable expansions):
488 command < $SOURCE > $TARGET
490 If you don't supply a space (for example, "<$SOURCE"), SCons will
491 not recognize the redirection.
493 - MSVC .res files are not rebuilt when icons change.
495 - The -c option does not clean up .sconsign files or directories
496 created as part of the build, and also does not clean up
497 SideEffect files (for example, Visual Studio .pdb files).
499 - Switching content signatures from "MD5" to "timestamp" and back
500 again can cause unusual errors. These errors can be cleared up by
501 removing all .sconsign files.
503 - When using multiple Repositories, changing the name of an include
504 file can cause an old version of the file to be used.
506 - There is currently no way to force use of a relative path (../*)
507 for directories outside the top-level SConstruct file.
509 - The Jar() Builder will, on its second or subsequent invocation,
510 package up the .sconsign files that SCons uses to track signatures.
511 You can work around this by using the SConsignFile() function
512 to collect all of the .sconsign information into a single file
513 outside of the directory being packaged by Jar().
515 - SCons does not currently have a way to detect that an intermediate
516 file has been corrupted from outside and should be rebuilt.
518 - Unicode characters in path names do not work in all circumstances.
520 - A stray source file in a BuildDir can prevent targets from being
521 (re)built when they should.
523 - SCons does not automatically rebuild LaTeX files when the file
524 has an undefined reference on the first build.
526 - Use of --implicit-cache with TargetSignatures('content') can,
527 for some changes, not rebuild a file when necessary.
529 - SCons does not currently automatically check out SConstruct or
530 SConscript files from SCCS, RCS or BitKeeper.
532 - No support yet for the following planned command-line options:
534 -d -e -l --list-actions --list-derived --list-where
535 -o --override -p -r -R -w --write-filenames
536 -W --warn-undefined-variables
540 Thank you for your interest, and please let us know how we can help
541 improve SCons for your needs.
544 knight at baldmt dot com
545 http://www.baldmt.com/~knight/
547 With plenty of help from the SCons Development team: