Re: 13-single-var-storage.patch

[Akim Demaille <akim at epita dot fr>]

Tom Tromey <tromey@redhat.com> writes:

> Akim> Patch is several chunks because it took me several steps to
> Akim> reach the right one.
> 
> That makes it a lot harder to read.  Please don't do that.

I didn't mean it :(  It really that I discovered side effects later
on.  I should have built a independent automake.in to reconstruct a
cleaner patch, sorry.  I will next time.

> Akim> -		       => $am_var_defs{'_am_installdirs'} || ''));
> Akim> +		       => $contents{'_am_installdirs'} || ''));
> 
> In general code outside the variable manipulation "module" should not
> directly use %contents.  I know some code does (the SOURCES/OBJECTS
> stuff), but that code is really, really old and could probably be
> removed.
> 
> This code used to use $am_var_defs, but that was wrong too.

I know.  I definitely know.  That's precisely what I'm doing: cleaning
up the handling of variables.  But I try to do it by logical chunks,
so this is just delayed.

> Incidentally do we give an error if the user tries to define
> _am_installdirs?  It seems like we should.  

Yes, definitely.  But first I am factoring everything, then it will be
easy in *one* place to have all the sanity checks we want.  I saw you
had that request in TODO, this is fine.  But really, I can't do
everything at once :(

> It also seems to me that one problem with the whole _am_installdirs
> idea is that we end up introducing a useless variable.  Ideally we'd
> leave useless variables out of Makefile.in.

If this variable is output, I have something wrong somewhere I didn't
notice.  To be honest, *because* I wish that there is no magic in *.am
files, my first intention was to have a variable actually output,
originally named INSTALLDIRS, and have mkinstalldirs use this macro.

The current implementation has some magic to *subtitute* INSTALLDIRS
at Automake time, and I wish it doesn't.  Since we can do it with more
dignified tool, more regular processing, I would really prefer the
latter choice.