[util/macros] factorize tests for xmlto

[Matthieu Herrb]

On Mon, Jan 04, 2010 at 07:29:51PM -0500, Gaetan Nadon wrote:
> 
> Let's see if we can communicate what this macro does.
> 
> # XORG_WITH_XMLTO
> # -------------------
> # Minimum version: 1.5.0
> #
> # Check for the availability of xmlto, a front-end to the xsl toolchain.
> # Set output variable XMLTO to the full path of the xmlto program found.
> # Allows user to override the value for XMLTO 
> # Define an Automake conditional HAVE_XMLTO
> # Provide a feature "--with-xmlto" where values can be:
> # auto:	set HAVE_XMLTO=1 if xmlto program is present
> # yes:	set HAVE_XMLTO=1 if xmlto program is present
> # no:	set HAVE_XMLTO=0
> #
> ]) # XORG_WITH_XMLTO
> 
> 
> I am wondering if we need the AC_ARG_VAR to supply a path to xmlto. I
> noticed only document kind of tools have this (e.g. asciidic, groff).
> All other tools in the toolchain (a total of about 32) are expected to
> be properly installed and in the PATH.

I have no idea on this. Iirc the autoconf documentation recommends that
AC_ARG_VAR is used with any variable used by AC_PATH_PROG, and this 
is how it is currently done in exiting uses cmlt.

> 
> The value of the XMLTO variable should not be unset when user says "no".
> The path to the tool and the decision of not using are separate issues.
> It's normal to have xmlto and not wanting to build the documentation.
> The Automake HAVE_XMLTO conditional is the variable to use for this
> decision, not a blank tool path. In addition, automake caches the value
> of XMLTO, so there could be trouble ahead.

If I understand things correclty, unsetting XMLTO is only local to the
configure script. It may be a bad coding trick to tell that we want
to ignore its value, but it won't affect the value seen by make later on.


> 
> Next I'll check the candidate users of this macro to test if it's really
> "generic" and useful. There is also the asciidoc in libXi which seems
> very similar to xmlto in usage.
> 

Thanks a lot for your help on this. I'm really not an expert in autotools,
So my initial patch was really just a Draft to start the discussion.

-- 
Matthieu Herrb