Re: Fwd: Suggestion about derived files and commands

[Doug Warner x81804]

Wayne Scott wrote:

> From: Doug Warner x81804 <address@hidden>
> > I wrote a little Extensions module that tried to make CONS aware of our
> > SCCS repository.  Unfortunately, it didn't work very well, because CONS
> > determined that I had modified my working copies outside of CONS and
> > decided to rebuild them from the pristine SCCS repository.  I made the
> > source files depend on the SCCS history file, which obviously doesn't work
> > when it comes to version control.  CONS may not need to be aware of
> > particular version control systems, but it may need to be aware that
> > version control differs from compiling sources to objects.
>
> I agree.  This is the problem.  You can't just use a build rule like
> Make can do because Cons is too clever.  It can't stand people messing
> with derived files.
>
> I can think of two ways to solve this problem.
>
>   * Add some sort of "weak" rules that will build a file if it doesn't
>     exist, but if it does exist it treat it like another source file.
>
>   * Have the ability to overload CONS's "file exists" primitive.  So
>     that when cons looks for a file in a directory if it is not found
>     we can quickly query the revision system.

Make also checks out new versions, even if the file exists locally.  At least
for RCS and SCCS, adding the notion of a locked source file to CONS would
work.  That might also work for CVS, but I'm not very familiar with CVS.  SCCS
itself only checks the permissions -- if it's writable, trust the programmer
and overlook it.  :-)

Doug