Re: (long) handling perl modules in mixed language source packages

[Alan D. Salewski]

On Fri, Aug 29, 2003 at 09:32:32AM +0200, Schleicher Ralph (LLI) spake thus:
> Alan D. Salewski writes:
> 
> > Note that it does not make sense to specify both the
> > '--enable-perlsysdirs' option and the '--with-perldir=DIR' options at
> > the same time; nevertheless, if both options are specified, the
> > '--enable-perlsysdirs' option is effectively ignored because the
> > '--with-perldir=DIR' option is more specific.
> 
> I would merge the two options into a single one:
> --without-perl-libdir AKA --with-perl-libdir=no uses $pkglibdir (the default).
> --with-perl-libdir AKA --with-perl-libdir=yes uses 'perl 
> -V:installsitelibperl'.
> --with-perl-libdir=DIR uses DIR as is.
> 
> -- 
> Ralph
 
Thanks for the suggestions, Ralph. Your way makes much better sense:
your 'configure' option name is better and your interface (one option
rather than two) is easier to understand. I've rearranged the original
code to implement the whole thing as you suggested, and it turns out
that the code is easier to understand, as well.

I'm now down to one macro, 'ads_PERL_LIBDIR', which I've included at the
end of this message. I'm trying to make this macro useful for anyone who
needs to configure and install perl modules, so I've also added a bunch
of documentation. Any comments or criticisms on this new macro would be
greatly appreciated.

One thing I noticed while making my changes for this version is that the
$pkglibdir shell variable is not available within the configure script;
it is only available in the generated Makefile.in files. In my original
message, I was building the equivalent of $pkglibdir by hand because I
did not think to use the $pkglibdir var directly (so I did not come
across this). Ralph's reply indicated the use of $pkglibdir so I read up
on it a bit and learned that it provides the same thing I was doing,
only as an automake provided facility. Still, you'll notice in the
'ads_PERL_LIBDIR' macro that I need to build the variable "by hand" in
the same way that automake does in the Makefile.in output. I would have
thought that $pkglibdir was available within 'configure' just as
$mandir, $bindir, etc. are. Am I missing something here?

I'm also considering making an equivalent macro for installing
architecture-specific perl modules (Perl's 'installsitearch'). If I do,
and anyone is interested, I'll send it to the list once I have
something.

-Al

P.S. I've included my 'ads_PROG_PERL.m4' file after the
     'ads_PERL_LIBDIR.m4' file because the latter requires something
     to define $PERL as a path to the perl interpreter. This is included
     as a convenience for anyone who might want to use
     'ads_PERL_LIBDIR' without writing their own test.

---------------------------8<-----ads_PERL_LIBDIR.m4--start
dnl -*-m4-*-

##
## $Id: ads_PERL_LIBDIR.m4,v 1.3 2003/08/29 20:35:52 al Exp $
##

dnl This macro provides for a new 'configure' option:
dnl     --with-perl-libdir=DIR
dnl
dnl which provides the following semantics:
dnl
dnl     --without-perl-libdir AKA --with-perl-libdir=no uses $pkglibdir (the 
default).
dnl     --with-perl-libdir AKA --with-perl-libdir=yes uses 'perl 
-V:installsitelib'.
dnl     --with-perl-libdir=DIR uses specified DIR
dnl
dnl This macro provides "autoconfiscated" software packages with a means
dnl of installing Perl library modules in a way that is consistent with
dnl other packages that use the GNU autotools, yet also allows perl modules
dnl to be installed like CPAN modules.
dnl
dnl Dependencies:
dnl ------------
dnl This macro expects that the shell variables $SED and $PERL are
dnl set and that their values are the paths to the 'sed' and 'perl'
dnl executables.
dnl
dnl The macro provides the 'PERL_LIBDIR' automake variable to indicate where
dnl perl library modules should be installed. It also provides the automake
dnl conditional 'USING_PERL_INSTALLSITELIB'. See below for details.
dnl
dnl The default behavior of this macro is to set up PERL_LIBDIR to install
dnl perl modules in $pkglibdir; this is to make it consistent with other
dnl automake macros in that the '--prefix=DIR' configure option is respected.
dnl The downside to this default behavior is that Perl scripts that need to
dnl access the installed modules may need to take special measures (add
dnl a 'use lib' pragma or manipulate @INC directly) to be able to find the
dnl modules; see the 'USING_PERL_INSTALLSITELIB' automake conditional below
dnl for one tool that may be used to handle this condition at configure time.
dnl The default behavior is what you get when the '--with-perl-libdir' option
dnl is not passed to configure, or when it is passed in the following forms:
dnl     --with-perl-libdir=no
dnl     --without-perl-libdir
dnl 
dnl When specified as
dnl     --with-perl-libdir
dnl or
dnl     --with-perl-libdir=yes
dnl the macro will determine where to install the perl modules by asking the
dnl perl interpreter where it will look for installed site libraries. This is
dnl how CPAN user's expect to be able to install Perl modules (that is, the
dnl installation procedure ask the existing Perl installation where it will
dnl be able to find installed modules, and then installs the modules
dnl accordingly), and would be the default behavior except for the fact that
dnl it ignores the '--prefix=DIR' configure option (when setting PERL_LIBDIR),
dnl and could therefore be destructive if the user was not expecting that.
dnl Packages that use this macro may wish to recommend this form of
dnl '--with-perl-libdir' to user's in a README or INSTALL file. This
dnl installation method is accomplished by extracting the directory path from
dnl the output of the command:
dnl     $ perl -V:installsitelib
dnl 
dnl The third and final way to use the '--with-perl-libdir' configure option
dnl is like this:
dnl     --with-perl-libdir=DIR
dnl When run this way, PERL_LIBDIR simply gets set to the value of DIR.
dnl
dnl
dnl To use this macro, simply put the following in your configure.in:
dnl     ads_PERL_LIBDIR
dnl
dnl This macro sets up the shell variable:
dnl
dnl     $PERL_LIBDIR, which will contain a directory name at the
dnl               end of the macro
dnl
dnl This macro sets up the automake var @PERL_LIBDIR@ with the value in the
dnl $PERL_LIBDIR shell variable. This automake var is provided for use in
dnl Makefile.am files.
dnl
dnl This macro also sets up the automake conditional 'USING_PERL_INSTALLSITELIB'
dnl to indicate whether or not the value of PERL_LIBIDR was set using the value
dnl returned from the perl interpreter for 'installsitelib'.
dnl
dnl
dnl CREDITS
dnl     * This macro was written by Alan D. Salewski <salewski AT 
worldnet.att.net>,
dnl       using code extracted from earlier efforts.
dnl
dnl     * The name and semantics of the '--with-perl-libdir' configure option 
are
dnl       an immense improvement over the original effort; these were suggested
dnl       by Ralph Schleicher <ralph.schleicher AT lli.liebherr.com>
dnl

AC_DEFUN(ads_PERL_LIBDIR, [
    AC_ARG_WITH(perl-libdir,

     changequote(<<, >>)dnl
<<  --with-perl-libdir[=ARG]
                          where to install perl modules [ARG=no, uses 
\$pgklibdir]>>dnl
     changequote([, ])dnl
    ,
    [ # AC_ARG_WITH: option if given
    AC_MSG_CHECKING(for where to install perl modules)
    # each condition sets 'using_perlsysdirs' to either "yes" or "no", and
    # sets 'PERL_LIBDIR' to a non-empty DIR value
    if test "$withval" = "no"; then
        # --with-perl-libdir=no AKA --without-perl-libdir uses $pkglibdir (dflt)
        using_perlsysdirs="no"

        # note that we're constructing pkglibdir as automake would, but not
        # using the shell variable directly; this is because automake (at least
        # as of 1.4-p5) only defines '$pkglibdir' in the generated Makefile.in
        # files, but not in 'configure.in'. We need it defined in configure
        # in order for the assignment to PERL_LIBDIR to work.
        PERL_LIBDIR=${libdir}/${PACKAGE}
        AC_MSG_RESULT(\$pkglibdir: ${libdir}/${PACKAGE})
    elif test -z "$withval" || \
         test "$withval" = "yes"; then
        # --with-perl-libdir AKA --with-perl-libdir=yes uses 'perl 
-V:installsitelib'
        using_perlsysdirs="yes"
        AC_MSG_RESULT(Perl's "installsitelib")

        AC_MSG_CHECKING(for perl installsitelib dir)
        PERL_LIBDIR=`$PERL '-V:installsitelib*' | \
                     $SED -e "s/^installsitelib=[']\(.*\)[']\$/\1/"`
        if test "${PERL_LIBDIR}" = "undef" || \
           test "${PERL_LIBDIR}X" = "X"; then
            tmp_valid_opts="`printf "\t"`"`$PERL -le 'print join $/."\t", @INC'`
            AC_MSG_ERROR([
    Perl\'s installsitelib is not defined, and this is the preferred
    location in which to install the perl libraries included with ${PACKAGE}.
    Of course, you may specify that the perl libraries be installed anywhere
    perl will find them (anywhere in the @INC array), but you must explicitely
    request where, as this is non-standard. You may specify where to place them
    by using the \'--with-perl-libdir=DIR\' option to \'configure\'. All of the
    following are in @INC:
$tmp_valid_opts
])
        fi
        AC_MSG_RESULT($PERL_LIBDIR)

    else
        # --with-perl-libdir=DIR, use user-specified directory
        using_perlsysdirs="no"
        PERL_LIBDIR="${withval}"
        AC_MSG_RESULT(specified dir: $withval)
        dnl DEBUG: FIXME: warn the user if dir not in @INC?
    fi
    ],
    [ # AC_ARG_WITH: option if not given, same as --without-perl-libdir
    AC_MSG_CHECKING(for where to install perl modules)

    # note that we're constructing pkglibdir as automake would, but not
    # using the shell variable directly; this is because automake (at least
    # as of 1.4-p5) only defines '$pkglibdir' in the generated Makefile.in
    # files, but not in 'configure.in'. We need it defined in configure
    # in order for the assignment to PERL_LIBDIR to work.
    PERL_LIBDIR=${libdir}/${PACKAGE}
    AC_MSG_RESULT(\$pkglibdir: ${libdir}/${PACKAGE})
    ])dnl end of AC_ARG_WITH(perl-libdir) macro

    AC_SUBST(PERL_LIBDIR)
    dnl register a conditional for use in Makefile.am files
    AM_CONDITIONAL(USING_PERL_INSTALLSITELIB, test x$using_perlsysdirs = x$yes)
])
---------------------------8<-----ads_PERL_LIBDIR.m4----end


---------------------------8<-----ads_PROG_PERL.m4----start
dnl -*- m4 -*-

##
## $Id: ads_PROG_PERL.m4,v 1.1 2003/08/29 21:04:59 al Exp $
##

dnl ads_PROG_PERL([required_perl_version])
dnl
dnl This macro tests for the existence of a perl interpreter on the
dnl target system. By default, it looks for perl version 5.005 or
dnl newer; you can change the default version by passing in the
dnl optional 'required_perl_version' argument, setting it to the perl
dnl version you want. The format of the 'required_perl_version' argument
dnl string is anything that you could legitimately use in a perl
dnl script, but see below for a note on the format of the perl version
dnl argument and compatibility with older perl interpreters.
dnl
dnl If no perl interpreter of the the required minimum version is found,
dnl then we bomb out with an error message.
dnl
dnl To use this macro, just drop it in your configure.in file as
dnl indicated in the examples below. Then use @PERL@ in any of your
dnl files that will be processed by automake; the @PERL@ variable
dnl will be expanded to the full path of the perl interpreter.
dnl
dnl Examples:
dnl     ads_PROG_PERL              (looks for 5.005, the default)
dnl     ads_PROG_PERL()            (same effect as previous)
dnl     ads_PROG_PERL([5.006])     (looks for 5.6.0, preferred way)
dnl     ads_PROG_PERL([5.6.0])     (looks for 5.6.0, don't do this)
dnl
dnl Note that care should be taken to make the required perl version
dnl backward compatible, as explained here:
dnl     http://www.perldoc.com/perl5.8.0/pod/func/require.html
dnl That is why the '5.006' form is preferred over '5.6.0', even though
dnl both are for perl version 5.6.0
dnl
dnl CREDITS
dnl     * This macro was written by Alan D. Salewksi <salewski AT 
worldnet.att.net>

AC_DEFUN(ads_PROG_PERL, [
    req_perl_version="$1"
    if test -z "$req_perl_version"; then
        req_perl_version="5.005"
    fi
    AC_PATH_PROG(PERL, perl)
    if test -z "$PERL"; then
        AC_MSG_ERROR([perl not found])
    fi
    $PERL -e "require ${req_perl_version};" || {
        AC_MSG_ERROR([perl $req_perl_version or newer is required])
    }
])
---------------------------8<-----ads_PROG_PERL.m4------end

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