/perl/Git/LoadCPAN.pm
Perl | 104 lines | 82 code | 17 blank | 5 comment | 11 complexity | a7992cadc0d9390a1a2cb3252c5c5f99 MD5 | raw file
- package Git::LoadCPAN;
- use 5.008;
- use strict;
- use warnings $ENV{GIT_PERL_FATAL_WARNINGS} ? qw(FATAL all) : ();
- =head1 NAME
- Git::LoadCPAN - Wrapper for loading modules from the CPAN (OS) or Git's own copy
- =head1 DESCRIPTION
- The Perl code in Git depends on some modules from the CPAN, but we
- don't want to make those a hard requirement for anyone building from
- source.
- Therefore the L<Git::LoadCPAN> namespace shipped with Git contains
- wrapper modules like C<Git::LoadCPAN::Module::Name> that will first
- attempt to load C<Module::Name> from the OS, and if that doesn't work
- will fall back on C<FromCPAN::Module::Name> shipped with Git itself.
- Usually distributors will not ship with Git's Git::FromCPAN tree at
- all via the C<NO_PERL_CPAN_FALLBACKS> option, preferring to use their
- own packaging of CPAN modules instead.
- This module is only intended to be used for code shipping in the
- C<git.git> repository. Use it for anything else at your peril!
- =cut
- # NO_PERL_CPAN_FALLBACKS_STR evades the sed search-replace from the
- # Makefile, and allows for detecting whether the module is loaded from
- # perl/Git as opposed to perl/build/Git, which is useful for one-off
- # testing without having Error.pm et al installed.
- use constant NO_PERL_CPAN_FALLBACKS_STR => '@@' . 'NO_PERL_CPAN_FALLBACKS' . '@@';
- use constant NO_PERL_CPAN_FALLBACKS => (
- q[@@NO_PERL_CPAN_FALLBACKS@@] ne ''
- and
- q[@@NO_PERL_CPAN_FALLBACKS@@] ne NO_PERL_CPAN_FALLBACKS_STR
- );
- sub import {
- shift;
- my $caller = caller;
- my %args = @_;
- my $module = exists $args{module} ? delete $args{module} : die "BUG: Expected 'module' parameter!";
- my $import = exists $args{import} ? delete $args{import} : die "BUG: Expected 'import' parameter!";
- die "BUG: Too many arguments!" if keys %args;
- # Foo::Bar to Foo/Bar.pm
- my $package_pm = $module;
- $package_pm =~ s[::][/]g;
- $package_pm .= '.pm';
- eval {
- require $package_pm;
- 1;
- } or do {
- my $error = $@ || "Zombie Error";
- if (NO_PERL_CPAN_FALLBACKS) {
- chomp(my $error = sprintf <<'THEY_PROMISED', $module);
- BUG: The '%s' module is not here, but NO_PERL_CPAN_FALLBACKS was set!
- Git needs this Perl module from the CPAN, and will by default ship
- with a copy of it. This Git was built with NO_PERL_CPAN_FALLBACKS,
- meaning that whoever built it promised to provide this module.
- You're seeing this error because they broke that promise, and we can't
- load our fallback version, since we were asked not to install it.
- If you're seeing this error and didn't package Git yourself the
- package you're using is broken, or your system is broken. This error
- won't appear if Git is built without NO_PERL_CPAN_FALLBACKS (instead
- we'll use our fallback version of the module).
- THEY_PROMISED
- die $error;
- }
- my $Git_LoadCPAN_pm_path = $INC{"Git/LoadCPAN.pm"} || die "BUG: Should have our own path from %INC!";
- require File::Basename;
- my $Git_LoadCPAN_pm_root = File::Basename::dirname($Git_LoadCPAN_pm_path) || die "BUG: Can't figure out lib/Git dirname from '$Git_LoadCPAN_pm_path'!";
- require File::Spec;
- my $Git_pm_FromCPAN_root = File::Spec->catdir($Git_LoadCPAN_pm_root, '..', 'FromCPAN');
- die "BUG: '$Git_pm_FromCPAN_root' should be a directory!" unless -d $Git_pm_FromCPAN_root;
- local @INC = ($Git_pm_FromCPAN_root, @INC);
- require $package_pm;
- };
- if ($import) {
- no strict 'refs';
- *{"${caller}::import"} = sub {
- shift;
- use strict 'refs';
- unshift @_, $module;
- goto &{"${module}::import"};
- };
- use strict 'refs';
- }
- }
- 1;