[libpackage-variant-perl] 04/23: alternate synopsis for named variants

[Jonas Smedegaard]

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js pushed a commit to branch master
in repository libpackage-variant-perl.

commit ca6d96a268693e998034e23a4506964df4f0465b
Author: Christian Walde <walde.christian at googlemail.com>
Date:   Sat Jul 25 19:03:54 2015 +0200

    alternate synopsis for named variants
---
 lib/Package/Variant.pm | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/lib/Package/Variant.pm b/lib/Package/Variant.pm
index 06cf0bf..091850f 100644
--- a/lib/Package/Variant.pm
+++ b/lib/Package/Variant.pm
@@ -135,6 +135,8 @@ Package::Variant - Parameterizable packages
 
 =head1 SYNOPSIS
 
+Creation of anonymous variants:
+
   # declaring a variable Moo role
   package My::VariableRole::ObjectAttr;
   use strictures 1;
@@ -168,6 +170,50 @@ Package::Variant - Parameterizable packages
   my $obj = My::Class::WithObjectAttr->new;
   $obj->some_obj; # returns a Some::Class instance
 
+And the same thing, only with named variants:
+
+  # declaring a variable Moo role that can be named
+  package My::VariableRole::ObjectAttrNamed;
+  use strictures 1;
+  use Package::Variant importing => ['Moo::Role'],
+    subs => [ qw(has around before after with) ];
+  use Module::Runtime 'module_notional_filename'; # only if you need protection
+
+  # this method is run at variant creation time to determine its custom
+  # package name. it can use the arguments or do something entirely else.
+  sub make_variant_package_name {
+    my ($class, $package, %arguments) = @_;
+    $package = "Private::$package"; # you can munge the input here if you like
+    # only if you *need* protection
+    die "Won't clobber $package" if $INC{module_notional_filename $package};
+    return $package;
+  }
+
+  # same as in the example above, except for the argument list. in this example
+  # $package is the user input, and
+  # $target_package is the actual package in which the variant gets installed
+  sub make_variant {
+    my ($class, $target_package, $package, %arguments) = @_;
+    my $name = $arguments{name};
+    has $name => (is => 'lazy');
+    install "_build_${name}" => sub {return $arguments{class}->new};
+  }
+
+  # using the role
+  package My::Class::WithObjectAttr;
+  use strictures 1;
+  use Moo;
+  use My::VariableRole::ObjectAttrNamed;
+
+  # create the role under a specific name
+  ObjectAttrNamed "My::Role" => (name => 'some_obj', class => 'Some::Class');
+  # and use it
+  with "Private::My::Role";
+
+  # using our class
+  my $obj = My::Class::WithObjectAttr->new;
+  $obj->some_obj; # returns a Some::Class instance
+
 =head1 DESCRIPTION
 
 This module allows you to build a variable package that contains a package

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