Re: Implementing a plugin-like module

[Sam Varshavchik]

Stefano Lattarini writes:

> A quick workaround to obtain this behaviour is to write your custom/rules
> defintion in a `.am' fragment in your source tree, and then include it
> from all the Makefile.am files that need it:
>
>   $ cat my-rules.am
>   my_variable = ...
>   .ctpl.c:
>         # rules to create a C file from a template `.ctpl'.
>
>   $ cat lib/Makefile.am
>   include  $(top_srcdir)/my-rules.am
>   ... [specific rules]
>
>   $ cat src/Makefile.am
>   include  $(top_srcdir)/my-rules.am
>   ... [other specific rules]

…

> There's no need to install an `.am' file there in order to use it with the
> `include' directive.

I saw that, when I was rooting around in automake -- that it attempts to  
expand relative include statements in Makefile.am, rather than leaving them  
in Makefile.in, and have gmake handle them.

It just didn't register to me that I don't need to add the .am file into  
make dist, since automake handles the inclusion.

I guess I can whip-up something analogous to gettextize, that symlinks  
the .am file from $top_srcdir, and adds the include statement to  
Makefile.am, if it's not there already. That should do it.

I also came up with a different solution last night. I install something  
like this into /usr/share/aclocal:

AC_DEFUN([LIBX_INIT],[
PKG_PROG_PKG_CONFIG
PKG_CHECK_EXISTS([libx],[:],[AC_MSG_ERROR([libx not found])])

libx_pkgdatadir="`$PKG_CONFIG --variable=pkgdatadir libx`"

LIBX_AM="include $libx_pkgdatadir/msgdispatcher.am"
AC_SUBST([LIBX_AM])
])

Then, I add

LIBX_INIT

to the configure.ac and add

@LIBX_AM@

in Makefile.am; and aclocal ends up automatically adding the m4 macro to  
aclocal.m4, which gets expanded into configure.in. At runtime, configure  
picks up the toolkit's installation directory, and creates an include  
statement that references it, which gets SUBST-ed into the Makefile.

Rather than having automake handle the inclusion, it's left up to gmake; but  
my build-rules are already gmake-specific, and this wouldn't be an  
additional requirement.

Thanks.

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