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 0.95:
31 - All Builder calls (both built-in like Program(), Library(),
32 etc. and customer Builders) now always return a list of target
33 Nodes. If the Builder only builds one target, the Builder
34 call will now return a list containing that target Node, not
35 the target Node itself as it used to do.
37 This change should be invisibile to most normal uses of the
38 return values from Builder calls. It will cause an error if the
39 SConscript file was performing some direct manipulation of the
40 returned Node value. For example, an attempt to print the name
41 of a target returned by the Object() Builder:
43 target = Object('foo.c')
47 Will now need to access the first element in the list returned by
50 target = Object('foo.c')
54 This change was introduced to make the data type returned by Builder
55 calls consistent (always a list), regardless of platform or number
58 - The SConsignFile() function now uses an internally-supplied
59 SCons.dblite module as the default DB scheme for the .sconsign file.
60 If you are using the SConsignFile() function without an explicitly
61 specified dbm_module argument, this will cause all of your targets
62 to be recompiled the first time you use SCons 0.96. To preserve the
63 previous behavior, specify the "anydbm" module explicitly:
66 SConsignFile('.sconsign_file_name', anydbm)
68 - The internal format of .sconsign files has been changed. This might
69 cause warnings about "ignoring corrupt .sconsign files" and rebuilds
70 when you use SCons 0.96 for the first time in a tree that was
71 previously built with SCons 0.95 or earlier.
73 - The scan_check function that can be supplied to a custom Scanner now
74 must take two arguments, the Node to be checked and a construction
75 environment. It previously only used the Node as an argument.
77 - The internal Scanner.add_skey() method no longer works for the
78 default scanners, which now use construction variables to hold their
79 lists of suffixes. If you had a custom Tool specification that was
80 reaching into the internals in this way to add a suffix to one of
81 the following scanner, you must now add the suffix to a construction
82 environment through which you plan to call the scanner, as follows:
84 CScan.add_skey('.x') => env.Append(CPPSUFFIXES = ['.x'])
85 DScan.add_skey('.x') => env.Append(DSUFFIXES = ['.x'])
86 FortranScan.add_skey('.x') => env.Append(FORTRANSUFFIXES = ['.x'])
88 - The "node_factory" and "scanner" keyword arguments to the Builder()
89 function have been removed. In their place, the separate and more
90 flexible "target_factory," "source_factory," "target_scanner" and
91 "source scanner" keywords should be used instead.
93 - SCons now treats file "extensions" that contain all digits (for
94 example, "file.123") as part of the file basename, for easier
95 handling of version numbers in the names of shared libraries
96 and other files. Builders will now add their file extensions to
97 file names specified with all-digit extensions. If you need to
98 generate a file with an all-digit extension using a Builder that
99 adds a file extension, you can preserve the previous behavior by
100 wrapping the file name in a File() call.
102 - The behavior of the env.Append() and env.Prepend() methods has
103 changed when appending a string value to a UserList, or vice versa.
104 They now behave like normal Python addition of a string to
105 a UserList. Given an initialization and an env.Append() call like:
107 env = Environment(VAR1=UserList(['foo']), VAR2='foo')
108 env.Append(VAR1='bar', VAR2=UserList(['bar'])
110 The resulting values of $VAR1 and $VAR2 will now be ['foo', 'b',
111 'a', 'r'] and ['f', 'o', 'o', 'bar'], respectively. This is because
112 Python UserList objects treat strings as sequences of letters when
113 adding them to the value of the UserList.
115 The old behavior of yielding $VAR1 and $VAR2 values of ['foo',
116 'bar'] when either variable is a UserList object now requires that
117 the string variables be enclosed in a list:
119 env = Environment(VAR1=UserList(['foo']), VAR2=['foo'])
120 env.Append(VAR1='bar', VAR2=UserList(['bar']))
122 Note that the SCons behavior when appending to normal lists has
123 *not* changed, and the behavior of all of the default values that
124 SCons uses to initialize all construction variables has *not*
125 changed. This change *only* affects any cases where you explicitly
126 use UserList objects to initialize or append to a variable.
128 Please note the following FUTURE changes that you may wish to prepare
131 - When compiling with Microsoft Visual Studio, SCons currently adds
132 the ATL and MFC directories to the INCLUDE and LIB environment
133 variables by default. This default behavior will be changed in
134 a future release; the current plan is to change it for the 0.97
135 release (next beta release).
137 Whether or not the ATL and MFC directories are added to these
138 environment variables is now controlled by a new MSVS_USE_MFC_DIRS
139 *construction* variable. Setting this variable to a non-zero
140 value when you initialize an Environment will ensure that these
141 directories will be included in your external path(s) even when
142 the default behavior changes:
144 env = Environment(MSVS_USE_MFC_DIRS = 1)
146 The MSVS_USE_MFC_DIRS variable may, of course, be set to 0 (or
147 None) to prevent SCons from adding the ATL and MFC directories to
148 the INCLUDE and LIB environment variables.
150 SCons is developed with an extensive regression test suite, and a
151 rigorous development methodology for continually improving that suite.
152 Because of this, SCons is of sufficient quality that you can use it
153 for real work. The "beta" status of the release reflects that we
154 still may change interfaces in future releases, which may require
155 modifications to your SConscript files. We strive to hold these
156 changes to a minimum.
158 Nevertheless, please heed the following disclaimers:
160 - Please report any bugs or other problems that you find to our bug
161 tracker at our SourceForge project page:
163 http://sourceforge.net/tracker/?func=add&group_id=30337&atid=398971
165 We have a reliable bug-fixing methodology already in place and
166 strive to respond to problems relatively quickly.
168 - Documentation is spottier than we'd like. You may need to dive
169 into the source code to figure out how to do something. Asking
170 questions on the scons-users mailing list is also welcome. We
171 will be addressing the documentation in upcoming releases, but
172 would be more than glad to have your assistance in correcting this
175 In particular, the "SCons Design" documentation on the SCons web
176 site is currently out of date, as we made significant changes to
177 portions of the interface as we figured out what worked and what
178 didn't during implementation.
180 - There may be performance issues. Improving SCons performance
181 is an ongoing priority. If you still find the performance
182 unacceptable, we would very much like to hear from you and learn
183 more about your configuration so we can optimize the right things.
185 - Error messages don't always exist where they'd be helpful.
186 Please let us know about any errors you ran into that would
187 have benefitted from a (more) descriptive message.
189 KNOWN PROBLEMS IN THIS RELEASE:
191 For a complete list of known problems, consult the SCons bug tracker
194 http://sourceforge.net/tracker/?atid=398971&group_id=30337&func=browse
196 - Support for parallel builds (-j) does not work on WIN32 systems
197 prior to *official* Python release 2.2 (not 2.2 pre-releases).
199 Prior to Python 2.2, there is a bug in Python's Win32
200 implementation such that when a thread spawns an external command,
201 it blocks all threads from running. This breaks the SCons
202 multithreading architecture used to support -j builds.
204 We have included a patch file, os_spawnv_fix.diff, that you can
205 use if you you want to fix your version of Python to support
206 parallel builds in SCons.
208 - Again, the "SCons Design" documentation on the SCons web
209 site is currently out of date. Take what you read there with a
212 - On Win32 systems, you must put a space between the redirection
213 characters < and >, and the specified files (or construction
214 variable expansions):
216 command < $SOURCE > $TARGET
218 If you don't supply a space (for example, "<$SOURCE"), SCons will
219 not recognize the redirection.
221 - MSVC .res files are not rebuilt when icons change.
223 - The -c option does not clean up .sconsign files or directories
224 created as part of the build, and also does not clean up
225 SideEffect files (for example, Visual Studio .pdb files).
227 - Switching content signatures from "MD5" to "timestamp" and back
228 again can cause unusual errors. These errors can be cleared up by
229 removing all .sconsign files.
231 - When using multiple Repositories, changing the name of an include
232 file can cause an old version of the file to be used.
234 - There is currently no way to force use of a relative path (../*)
235 for directories outside the top-level SConstruct file.
237 - The Jar() Builder will, on its second or subsequent invocation,
238 package up the .sconsign files that SCons uses to track signatures.
239 You can work around this by using the SConsignFile() function
240 to collect all of the .sconsign information into a single file
241 outside of the directory being packaged by Jar().
243 - SCons does not currently have a way to detect that an intermediate
244 file has been corrupted from outside and should be rebuilt.
246 - Unicode characters in path names do not work in all circumstances.
248 - A stray source file in a BuildDir can prevent targets from being
249 (re)built when they should.
251 - SCons does not automatically rebuild LaTeX files when the file
252 has an undefined reference on the first build.
254 - Use of --implicit-cache with TargetSignatures('content') can,
255 for some changes, not rebuild a file when necessary.
257 - SCons does not currently automatically check out SConstruct or
258 SConscript files from SCCS, RCS or BitKeeper.
260 - No support yet for the following planned command-line options:
262 -d -e -l --list-actions --list-derived --list-where
263 -o --override -p -r -R -w --write-filenames
264 -W --warn-undefined-variables
268 Thank you for your interest, and please let us know how we can help
269 improve SCons for your needs.
272 knight at baldmt dot com
273 http://www.baldmt.com/~knight/
275 With plenty of help from the SCons Development team: