问题
I'd like to get scons to read a previous version number from a file, update a source file with a new version number and current date and then write the number back to the original file ready for the next build.
This needs to happen only when the target is out of date. IOW the version number doesn't change if no build takes place. The original file is source controlled and isn't a source file else it could trigger another build on check-in (due to CI). CLARIFICATION From scons' point of view the code will always be out of date due to the auto-generated source file but scons will only be run from a Continuous Integration job (Jenkins) when a SCM change is detected.
I've looked into AddPostMethod, but this seems to fire for all files within the list of source files.Command and Builder methods use the VARIANT_DIR so I can't edit these files and then check them back in as they no longer map to the repo.
I'm hoping I'm just misunderstanding some of the finer details of scons else I'm running out of ideas!
Update Thinking this through some more, Tom's comment is correct. Although I have two files, one version controlled text file (non-source code) and one non-source controlled source file there is no way to check one file in and prevent a continuous build/check-in cycle. Jenkins will see the new text file and spin off a build, and scons will see the new generated file. So unless I delete the generated file at some point, although this seems to go against the workflow of both tools.
Does anyone have any method for achieving this? It seems pretty straightforward. Ultimately I just want to generate build numbers each time a build is started.
回答1:
From SCons User Guide section 8, Order-Only Dependencies, you can use the Requires method:
import time
# put whatever text you want in your version.c; this is just regular python
version_c_text = """
char *date = "%s";
""" % time.ctime(time.time())
open('version.c', 'w').write(version_c_text)
version_obj = Object('version.c')
hello = Program('hello.c',
LINKFLAGS = str(version_obj[0]))
Requires(hello, version_obj)
Two things to note: first you have to add the explicit Requires dependency. Second, you can't make version_obj a source of the Program builder, you have to cheat (here we pass it as a linkflag), otherwise you'll get an automatic full dependency on it.
This will update the version.c always, but won't rebuild just because version.c changed.
来源：https://stackoverflow.com/questions/17414213/get-scons-to-generate-a-new-build-number