Re: AM_SUBST_IGNORE = AC_SUBST without Makefile variable definition

[Alexandre Duret-Lutz]

>>> "SK" == Stepan Kasal <address@hidden> writes:

 SK> Hello,
 SK> On Tue, Oct 18, 2005 at 01:24:14PM +0200, Ralf Wildenhues wrote:
 >> > Please hold back the AM_SUBST_IGNORE until multiline substitutions in
 >> > Automake are solved.
 >> 
 >> I don't see why the solution to the problem of not substituting certain
 >> variables is dependent on the problem of how to handle multiline
 >> substitutions?

 SK> I wrote an answer yesterday, but by mistake I posted it to Ralf only.
 SK> In short, I'm not sure that the feature is necessary.

 SK> Ralf wrote me a very nice explanation, which convinced me.
 SK> In short, it is needed as the solution for PR/477.

 SK> Perhaps you could post the explanation here, Ralf?

 SK> I still think it should be implemented in Autoconf, see the patch below.

 SK> Would you like it this way?  If yes, I'll finish the patch and submit it
 SK> to autoconf-patches.

I'm not overly fond of this.  First of all, the name _NOTRACE
makes reference to an internal detail the average user knows
nothing about.  Secondly I think disabling the trace for an
AC_SUBST just because Automake shouldn't output it is wrong:
Automake is just one client amongst others of the "--trace"
interface, maybe somebody else has a tool that needs to know ALL
substitutions.  What I want is just a way to say "dear Automake,
please ignore this substitution when generating Makefile.ins";
i.e., I really want to talk to Automake, not to ask Autoconf to
hide things from any tool that trace for them.  Hence I think
this really belongs to Automake.

Originally, I wanted AM_SUBST_IGNORE to cause Automake to ignore
a previously defined AC_SUBST, so you could have

AC_SUBST([foo])

and later, perhaps outside the macro that defines 'foo' if it's
not yours, you would do

AM_SUBST_IGNORE([foo])

to tell Automake to ignore it.  I'm sure the name of _IGNORE
makes more sense in this usage.  But then I realized the two
lines would be often close to each other, and it was harmless to
call AC_SUBST from AM_SUBST_IGNORE, even if AC_SUBST is not
called.
-- 
Alexandre Duret-Lutz

Shared books are happy books.     http://www.bookcrossing.com/friend/gadl