[Scons-users] Code generation in SCons

[Bill Deegan]

We believe that issues been resolved by the migration to Python 3.5+ as
they improved some file i/o issues.
In addition we have an issue filed with another method to resolve,
basically a post action which does nothing but wait until the file is
writable.  (See:https://github.com/SCons/scons/issues/3592)
(Very clever)


On Thu, Apr 23, 2020 at 11:32 PM Arvid Rosén <arvid at softube.com> wrote:

> There used to be issues with massive parallel builds and generated files
> on Windows. SCons would handle the dependencies correctly, but something
> with Python on Windows made the synchronization between threads unreliable
> so that the compiler would try to open the .c file for reading too early,
> and would get a permission error.
>
>
>
> I think this only happened when the .c file was written by Python though,
> and not by external tools.
>
>
>
> This might be fixed now, but I spent lots of time on it to implement
> workarounds, so watch out!
>
>
>
> Cheers,
>
> Arvid
>
>
>
>
>
> *From: *Scons-users <scons-users-bounces at scons.org> on behalf of Bill
> Deegan <bill at baddogconsulting.com>
> *Reply to: *SCons users mailing list <scons-users at scons.org>
> *Date: *Thursday, 23 April 2020 at 21:00
> *To: *SCons users mailing list <scons-users at scons.org>
> *Subject: *Re: [Scons-users] Code generation in SCons
>
>
>
> Erik,
>
>
>
> Please take a look at the yacc builder.
>
>
>
> It has similar functionality in that it reads a source file and spits out
> .c and .h files.
>
> SCons is fully capable of "doing the right thing" in such cases if the
> builder is properly constructed.
>
>
>
> -Bill
>
>
>
> On Thu, Apr 23, 2020 at 7:42 AM Mats Wichmann <mats at wichmann.us> wrote:
>
> Someone else will hopefully help... this is the sort of thing I *believe*
> Depends() was intended for. And emitters. Also, there's a protobuf builder
> or two floating around somewhere if that helps (see the wiki)
>
> On April 23, 2020 7:49:05 AM MDT, Erik Kazandjian <
> erik.kazandjian at gmail.com> wrote:
>
> I start from a YANG file. From that file I create proto fiels for Google
> protobuf and heade files. These files are than given to 'standard' builders
> who generate libraries out of them. But as said before because these proto
> files and C files (both .c and .h) get generated SCons can not pick them up
> the first time as they are not there, the second time he considers them to
> have changed only the thirds time Scons sees that the files are
> identical and doesn't build them any longer. Is there a way to recalculate
> the md5 database after building ?
>
>
>
> On Thu, 23 Apr 2020 at 15:14, Mats Wichmann <mats at wichmann.us> wrote:
>
> On 4/23/20 2:21 AM, Erik Kazandjian wrote:
> > Hi,
> >
> > I've created a builder that generates C code nad header files from a
> > yang file. The problem I'm having is the first I build these c and h
> > files are not there so scons rebuilds them , but than the second time
> > when I build scons decides that the C and header files have changes and
> > so it rebuilds again generating the exact same c and h file, do only the
> > third time it builds it decide bot to rebuild anything. Is there a way
> > in scons to get around this or do I have to write a custom decider
> myself ?
>
> Since there's existing practice (lex, swig and yacc included with SCons
> itself as well as external efforts), there should be a way to get it to
> work. Perhaps if you share what you're doing?  There is a bit of
> plumbing to get hooked up.
>
>
>
>
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> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>
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