Re: Adding an external project to autoconf

[Ralf Wildenhues]

* Dan Smithers wrote on Mon, Sep 14, 2009 at 11:18:53AM CEST:
> >> How can I tell autoconf to run the configure without worrying about it?
> > 
> > AC_CONFIG_SUBDIRS([zlib])
> > > will cause zlib/configure to be run if it exists in the source tree.
> 
> I had been using
> AC_CONFIG_SUBDIRS(zlib dir1 dir2)
> 
> I never really worked out whether there is any difference between () and
> ([]).

Generally, it is good style to use one level of quoting:
  AC_CONFIG_SUBDIRS([zlib dir1 dir2])

That will still allow macros to be expanded inside (say, if you had
defined 'dir1' to be an m4 macro) but will not read it as multiple
arguments (say, if one of the strings had a comma in its name).  You
use two levels of quoting for things that really need to be literals:
  AC_CONFIG_SUBDIRS([[zlib dir1 dir2]])

In this case, even if you added
  AC_DEFUN([dir1], [dir3 dir4])

before the above line, 'dir1' would not be expanded by m4.

Hope that helps.

Cheers,
Ralf