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local/lib/perl5/Module/Implementation.pm  view on Meta::CPAN

package Module::Implementation;
# git description: v0.08-2-gd599347
$Module::Implementation::VERSION = '0.09';

use strict;
use warnings;

use Module::Runtime 0.012 qw( require_module );
use Try::Tiny;

# This is needed for the benefit of Test::CleanNamespaces, which in turn loads
# Package::Stash, which in turn loads this module and expects a minimum
# version.
unless ( exists $Module::Implementation::{VERSION}
    && ${ $Module::Implementation::{VERSION} } ) {

    $Module::Implementation::{VERSION} = \42;
}

my %Implementation;

sub build_loader_sub {
    my $caller = caller();

    return _build_loader( $caller, @_ );
}

sub _build_loader {
    my $package = shift;
    my %args    = @_;

    my @implementations = @{ $args{implementations} };
    my @symbols = @{ $args{symbols} || [] };

    my $implementation;
    my $env_var = uc $package;
    $env_var =~ s/::/_/g;
    $env_var .= '_IMPLEMENTATION';

    return sub {
        my ( $implementation, $loaded ) = _load_implementation(
            $package,
            $ENV{$env_var},
            \@implementations,
        );

        $Implementation{$package} = $implementation;

        _copy_symbols( $loaded, $package, \@symbols );

        return $loaded;
    };
}

sub implementation_for {
    my $package = shift;

    return $Implementation{$package};
}

sub _load_implementation {
    my $package         = shift;
    my $env_value       = shift;
    my $implementations = shift;

    if ($env_value) {
        die "$env_value is not a valid implementation for $package"
            unless grep { $_ eq $env_value } @{$implementations};