Can ExtUtils::MakeMaker recommend to install optional modules?

[voj]

In ExtUtils::MakeMaker you specify required modules in PREREQ_PM. I have a module that recommends the GraphViz module but it can also be installed without. Can I somehow add a rule to Makefile.PL that triggers an attempt to install GraphViz? So if you have already installed the graphviz binary (which is needed by GraphViz module), installation of my module should also install GraphViz. But if this fails, because of missing graphviz binary, you should only get a message.

[Dallaylaen]

This article sums up dependencies pretty well.

Here's how you specify recommended/suggested dependencies:

use ExtUtils::MakeMaker 6.64;

WriteMakefile(
    # other stuff
    META_MERGE => {
        "meta-spec" => { version => 2 },
        prereqs => {
            test => {
                recommends => {
                    'CPAN::Meta' => '2.120900',
                },
            },
            runtime => {
                recommends => {
                    'Text::CSV_XS' => 0,
                },
            },
        },
    },
);

[1nickt]

Here's how you specify recommended/suggested dependencies:

For the record: there is a difference between recommends and suggests.

The two (and requires and conflicts) exist so the module author has more control over, well, recommendations and suggestions. Not all versions of all clients support the newest spec, but recent ones do.

• CPAN::Meta::Spec prereqs section
• Neil Bowers blog on specifying dependencies

Hope this helps!

[Anonymous Monk]

What if I don't want the recommended additional packages? How can I force the build to ignore the recommends? In my case a command line tool recommends, through a chain of dependencies, that I install the X server. I really don't want to do that.

[Dallaylaen]

Default cpan client has recommends_policy and suggests_policy options under o conf just for that. Couldn't find anything in cpanm, but maybe it can, too. No idea about cpanplus.

Btw installing raw CPAN on perlbrew was nontrivial, though not complicated after all. Maybe brew should bundle a script for that...

[DrHyde]

...
PREREQ_PM => {
  ...
  (`which graphviz`) ? (GraphViz => '2.08') : ())
},
...

Adapt as required to make it portable :-)

[Anonymous Monk]

No.

If you're using any of cpan/cpanp/cpanm... they will notice what MakeMaker says, and attempt to install the prerequisites

You can use ExtUtils::AutoInstall - Automatic install of dependencies via CPAN

or Module::AutoInstall - Automatic install of dependencies via CPAN

[Anonymous Monk]

yes! http://grokbase.com/t/perl.org/module-authors/2009/10/how-can-i-tell-makemaker-to-insert-recommended-modules-into-meta-yml/16vuqyqk4yiugwsm43ttanhirbry

[Anonymous Monk]

yes!...

That has nothing to do with the question asked. META is generated from PREREQ_PM. MakeMaker doesn't download modules, cpan does.