[Scons-users] Let directory depend on file? (auto generated sources)

[Gary Oberbrunner]

What we do here in a similar situation is something like this:
http://www.scons.org/wiki/DynamicSourceGenerator
It's not for the faint of heart, but it can be done.

On Wed, Nov 26, 2014 at 12:21 PM, Stijn De Ruyck <Stijn.DeRuyck at onsemi.com>
wrote:

>  *You have to specify one of the resulting files "autogen/x.cc" as target
> instead,*
>
>  If all else fails, maybe this could work, yes.... I just need to pick an
> autogen file that will usually always be generated, no matter the contents
> of mst.odl. But it's not a 100% "clean" solution :p
>
>  ------------------------------
> *Van:* Scons-users [scons-users-bounces at scons.org] namens Stijn De Ruyck [
> Stijn.DeRuyck at onsemi.com]
> *Verzonden:* woensdag 26 november 2014 18:11
> *Aan:* dl9obn at darc.de; SCons users mailing list
>
> *Onderwerp:* Re: [Scons-users] Let directory depend on file? (auto
> generated sources)
>
>   Hi Dirk,
>
>  Well, I kind of suspected using Dir('autogen') as target was a bit of
> wishful thinking :) but SCons has amazed me so far, so I didn't hurt to try
> :p
> I had to leave the office afterwards and won't be back until next week,
> but I sure would like to come up with a solution by the time I get back...
>
>  The problem with what you're suggesting is that I don't really know what
> files installModel.sh (which calls another binary) will generate in the
> autogen directory. I know now, but that can change depending on what's
> declared in mst.odl in the future, and we'd like to keep this automated...
>
>  What I could do is have autogen deleted by scons before every build step
> (someway somehow?), that would trigger it's recreation like you said and
> make sure builds are started from the most recent set of autogen files, but
> that's too rough and would run installModel.sh everytime, even when it's
> not needed.
>
>  That's also what we do with Make right now; a brute-force approach: on
> make, if mst.odl has changed, call make clean, run installModel, then
> rebuild the entire thing (and provide all the autogen targets manually in
> the makefile).
> We were hoping to do this nicer/faster with SCons...
>
>  Best regards,
>
>  Stijn
>
>  ------------------------------
> *Van:* Scons-users [scons-users-bounces at scons.org] namens Dirk Bächle [
> tshortik at gmx.de]
> *Verzonden:* woensdag 26 november 2014 17:46
> *Aan:* scons-users at scons.org
> *Onderwerp:* Re: [Scons-users] Let directory depend on file? (auto
> generated sources)
>
>   Hi Stijn,
>
> On 26.11.2014 12:25, Stijn De Ruyck wrote:
>
> Hi,
>
>  Consider following situation:
> - directory "autogen" containing .cc files generated by installModel.sh
> script.
> - file "mst.odl" is used by installModel.sh to generate the autogen files.
> - contents of autogen can vary depending on mst.odl (in other words,
> resulting sources in autogen are not known in advance)
> - if scons sees a change in mst.odl, it must first call installModel.sh to
> repopulate the autogen directory, then continue with figuring out
> dependencies and building what's needed. (Other sources depend largely on
> the autogen files. So if autogen is modified, scons should automatically
> trigger a (near) complete rebuild anyway.)
>
>  In other words, the autogen directory depends on mst.odl.
>
>   this statement is not quite correct. The "contents" of the autogen
> directory (created .cc files) depend on "etc/mst.odl".
>
>   How do I configure this?
>
>  What I had was this (not at the office right now, so code not 100%
> accurate):
>
>  SConstruct file:
> (...)
> autogen = env.Command(Dir('autogen'), 'etc/mst.odl',
> 'tools/build/installModel.sh with some args')
>
>
> Using a directory as target will not give you what you're actually trying
> to achieve. Like every other build system, SCons regards a directory to be
> up-to-date if it exists. So, after the first invocation your target
> "autogen" is always up-to-date and your shell script never gets called,
> until you remove the folder.
>
> You have to specify one of the resulting files "autogen/x.cc" as target
> instead, even better: specify all the created files as targets by writing a
> Builder+Emitter for your build step.
>
> Best regards,
>
> Dirk
>
>
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>


-- 
Gary
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