robustly list any Perl code's module dependencies

Category:	Utility Scripts
Author/Contact Info	/msg Aristotle
Description:	I just read hans_moleman's script and thought there has to be a more robust way to do this that doesn't rely on parsing sources and has better support for recursive dependencies than just reporting whether a toplevel dependency is satisfied. This module is the surprisingly simple result. It relies on the fact that you can put coderefs in `@INC`. Update: podmaster points out that not all pragmas are available everywhere, warnings being an obvious example, so they constitute a depency, too. I don't want to change the behaviour of this module however, therefor I added this to the CAVEATS section in the POD.
#!/usr/bin/perl -w package ListDependencies; use strict; unshift @INC, sub { local $_ = $_[1]; return unless /[[:upper:]]/; s/\.pm$//i; s/[\/:]/::/g; print STDERR $_, $/; }; 1; __END__ =head1 NAME ListDependencies.pm - list any Perl code's module dependencies =head1 SYNOPSIS perl -c -MListDependencies scriptname perl -MListDependencies -MModule::Name -e1 perl -MListDependencies -e'use Module::Name' =head1 DESCRIPTION This module prints the names of any modules any piece of Perl code compiled after it tries to load to C<STDERR>, but ignores C<use pragma;> directives. You should load this module prior to all others. The C<-M> command line switch to C<perl> is a good place to do so. Note that it won't prevent execution of the code you're trying to examine. If all you want to do is list dependencies for a piece of standalone code, you may want to use the C<-c> command line switch to C<perl> to check compile time dependencies. Be aware that this will leave you blind to any attempts to load modules dynamically at runtime. =head1 CAVEATS If your own custom modules use all-lowercase names, this module won't list them. This is intentional: all-lowercase names are reserved for Perl pragmas. Note that not all pragmas are available everywhere, so they may constitute a depency as well. L<warnings> is an obvious example. =head1 BUGS There is no way to specify a different output file handle than C<STDERR>. A proper version should include an C<import()> routine to take care of this. =head1 RESTRICTIONS The module only honours Unix, DOSish and MacOS directory separators. A more portable solution would have to rely on L<File::Spec>, but unfortunately that would require this module to import modules itself. Heisenberg's Dispersion Relation applies. :-) =head1 AUTHOR Aristotle Pagaltzis <pagaltzis at gmx dot de> =head1 COPYRIGHT Copyright 2002. This may be modified and distributed on the same terms as Perl.

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Re: robustly list any Perl code's module dependencies by simonflk (Pilgrim) on Oct 06, 2002 at 14:00 UTC
This is a nice trick, but it won't work if the script or or any modules that are loaded do a `use lib` or `unshift @INC` Something like this should work, as long as require is not overriden elsewhere: `package ShowDependencies; use strict; CORE::GLOBAL::require = \&show_require; sub show_require (;$) { my $module = shift; print STDERR $module, $/; my $retval = eval "CORE::require( $module )"; die $@ if $@; return $retval; } 1;` [download] There is also a module (Module::Dependency) on the CPAN that builds a list of dependencies. update:* added use strict -- simonflk	[reply] [d/l]

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Re: robustly list any Perl code's module dependencies
by simonflk (Pilgrim) on Oct 06, 2002 at 14:00 UTC

This is a nice trick, but it won't work if the script or or any modules that are loaded do a use lib or unshift @INC

Something like this should work, as long as require is not overriden elsewhere:

package ShowDependencies;
use strict;

*CORE::GLOBAL::require = \&show_require;

sub show_require (;$)  {
    my $module = shift;
    print STDERR $module, $/;
    my $retval = eval "CORE::require( $module )";
    die $@ if $@;
    return $retval;
}
1;
[download]

There is also a module (Module::Dependency) on the CPAN that builds a list of dependencies.

update:

-- simonflk

[reply]
[d/l]