[Scons-users] Finding targets which depend on a source file

[Stefan Ross]

I also have found myself wanting this feature.  Not because Scons is doing
the wrong thing, but because it's helpful when building SConscript files to
have this information.  For example, I recently did a big refactoring on a
codebase where I wasn't that familiar with the whole codebase, including
its dependencies.  So it's possible that I refactored some of the tools out
such that nothing depended on them, but there's no easy way to find this
out.  I could delete the tool, do a clean, and rebuild, but that's a slow
cycle.  Having Scons report such dependencies would be helpful.

I had other examples where I had output files with the same name in
different directories (I was moving things about).  Sometimes I got
confused about which version of the file was being referenced.  I know
there are other ways of finding these, but a single command to check if a
particular file had any other files depending on it would have been helpful.

Thanks

Stefan

On Wed, Nov 18, 2015 at 11:50 PM, Bill Deegan <bill at baddogconsulting.com>
wrote:

> scons will do what you are asking without you having to explicitly list
> them on  the command line.
> If it's doing the wrong thing, file a bug.
>
> I can't fathom a reason to do what you are asking to do.
> Can you supply a reason to your madness so that perhaps we can propose a
> way which make sense for scons?
>
> You can use the --tree=prune output as well to see what depends on what.
>
> -Bill
>
> On Wed, Nov 18, 2015 at 3:47 PM, William Blevins <wblevins001 at gmail.com>
> wrote:
>
>>
>>
>> On Wed, Nov 18, 2015 at 11:16 PM, Abhishek Rai <abhishekrai at gmail.com>
>> wrote:
>>
>>> Thanks for the prompt response William.
>>>
>>> On Wed, Nov 18, 2015 at 3:06 PM, William Blevins <wblevins001 at gmail.com>
>>> wrote:
>>> >
>>> > SCons already only builds targets that are not up-to-date, so what is
>>> the point of this script per say? I assume that you are always starting
>>> from a fresh repository clone of some kind?
>>>
>>> Yes.  In our git repository, we pull code from the origin several times
>>> every day.  After each pull, as far as scons goes, several build targets
>>> become out of date, causing it to rebuild them when we try to build all
>>> targets.  In our environment, it's safe to assume that code pulled from
>>> origin passes all builds and tests, therefore rebuilding locally is an
>>> overkill.
>>>
>>> >
>>> > The SCons paradigm generally maps Targets to Dependencies (Sources),
>>> so you would need to work backwards.  You might be able to get this
>>> information from "scons --dry-run --tree=<option>" with a clever parser,
>>> but this will require that SCons scan all the files even though it might
>>> not build targets.
>>>
>>> The --dry-run option unfortunately suffers from the similar limitation -
>>> it finds that most targets are out of date, including those unaffected by
>>> local changes.
>>>
>>
>> dry-run doesn't execute the build statements, so my point here was to get
>> the dependency tree output without compiling.  You can then find entries in
>> the tree that map to local changes (files shown by git status, etc); this
>> of course can give you the final target if you follow the tree to the root.
>> You will need a parser for the tree output which shouldn't be too
>> complicated, but it might not be efficient either.
>>
>>
>>>
>>> >
>>> > I am not sure if there is a better way.
>>> >
>>> > V/R,
>>> > William
>>>
>>> Thanks!
>>> Abhishek
>>>
>>> >
>>> > On Wed, Nov 18, 2015 at 10:53 PM, Abhishek Rai <abhishekrai at gmail.com>
>>> wrote:
>>> >>
>>> >> Hello,
>>> >>
>>> >> Is there any way in scons to list all targets which depend on a given
>>> source file?
>>> >>
>>> >> In the code base that I'm working on, we have a "pre-commit" script
>>> which verifies whether the changes in the commit break any targets.
>>> Currently, this script tries to build all targets.  Of course, some targets
>>> may not need rebuilding if the corresponding source files haven't changed
>>> since the previous build.  But given the dynamic nature of the code base,
>>> each run of the pre-commit script ends up building nearly all targets even
>>> if that commit affects only a small number of them.
>>> >>
>>> >> Having the ability to list all targets derived from a given source
>>> file will give us the ability to list out these targets first, and then
>>> only build those targets as part of the pre-commit workflow.
>>> >>
>>> >> Thanks!
>>> >> Abhishek
>>> >>
>>> >> _______________________________________________
>>> >> Scons-users mailing list
>>> >> Scons-users at scons.org
>>> >> https://pairlist4.pair.net/mailman/listinfo/scons-users
>>> >>
>>> >
>>> >
>>> > _______________________________________________
>>> > Scons-users mailing list
>>> > Scons-users at scons.org
>>> > https://pairlist4.pair.net/mailman/listinfo/scons-users
>>> >
>>>
>>> _______________________________________________
>>> Scons-users mailing list
>>> Scons-users at scons.org
>>> https://pairlist4.pair.net/mailman/listinfo/scons-users
>>>
>>>
>>
>> _______________________________________________
>> Scons-users mailing list
>> Scons-users at scons.org
>> https://pairlist4.pair.net/mailman/listinfo/scons-users
>>
>>
>
> _______________________________________________
> Scons-users mailing list
> Scons-users at scons.org
> https://pairlist4.pair.net/mailman/listinfo/scons-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://pairlist4.pair.net/pipermail/scons-users/attachments/20151119/3b605aef/attachment-0001.html>