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