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1 | package Moose::Policy; |
2 | |
3 | use strict; |
4 | use warnings; |
5 | |
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6 | our $VERSION = '0.01'; |
7 | |
8 | use Moose (); |
9 | use Carp 'confess'; |
10 | use Scalar::Util 'blessed'; |
11 | |
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12 | sub import { |
13 | shift; |
14 | |
15 | my $policy = shift || return; |
16 | |
17 | unless (Moose::_is_class_already_loaded($policy)) { |
18 | ($policy->require) or confess "Could not load policy module " . |
19 | "'$policy' because : $UNIVERSAL::require::ERROR"; |
20 | } |
21 | |
22 | my $package = caller(); |
23 | $package->can('meta') and |
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24 | croak("'$package' already has a meta() method, this is very problematic"); |
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25 | |
26 | my $metaclass = 'Moose::Meta::Class'; |
27 | $metaclass = $policy->metaclass($package) |
28 | if $policy->can('metaclass'); |
29 | |
30 | my %options; |
31 | |
32 | # build options out of policy's constants |
33 | $policy->can($_) and $options{":$_"} = $policy->$_($package) |
34 | for (qw( |
35 | attribute_metaclass |
36 | instance_metaclass |
37 | method_metaclass |
38 | )); |
39 | |
40 | # create a meta object so we can install &meta |
41 | my $meta = $metaclass->initialize($package => %options); |
42 | $meta->add_method('meta' => sub { |
43 | # we must re-initialize so that it works as expected in |
44 | # subclasses, since metaclass instances are singletons, this is |
45 | # not really a big deal anyway. |
46 | $metaclass->initialize((blessed($_[0]) || $_[0]) => %options) |
47 | }); |
48 | } |
49 | |
50 | 1; |
51 | |
52 | __END__ |
53 | |
54 | =pod |
55 | |
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56 | =head1 NAME |
57 | |
58 | Moose::Policy - moose-mounted police |
59 | |
60 | =head1 SYNOPSIS |
61 | |
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62 | package Foo; |
63 | |
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64 | use Moose::Policy 'Moose::Policy::FollowPBP'; |
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65 | use Moose; |
66 | |
67 | has 'bar' => (is => 'rw', default => 'Foo::bar'); |
68 | has 'baz' => (is => 'ro', default => 'Foo::baz'); |
69 | |
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70 | # Foo now has (get, set)_bar methods as well as get_baz |
71 | |
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72 | =head1 DESCRIPTION |
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73 | |
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74 | This module allows you to specify your project-wide or even company-wide |
75 | Moose meta-policy. |
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76 | |
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77 | Most all of Moose's features can be customized through the use of custom |
78 | metaclasses, however fiddling with the metaclasses can be hairy. Moose::Policy |
79 | removes most of that hairiness and makes it possible to cleanly contain |
80 | a set of meta-level customizations in one easy to use module. |
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81 | |
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82 | This is the first release of this module and it should not be considered to |
83 | be complete by any means. It is very basic implemenation at this point and |
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84 | will likely get more feature-full over time, as people request features. |
85 | So if you have a suggestion/need/idea, please speak up. |
86 | |
87 | =head2 What is a meta-policy? |
88 | |
89 | A meta-policy is a set of custom Moose metaclasses which can be used to |
90 | implement a number of customizations and restrictions on a particular |
91 | Moose class. |
92 | |
93 | For instance, L<Moose::Policy::SingleInheritence> enforces that all |
94 | specified Moose classes can only use single inheritence. It does this |
95 | by trapping the call to C<superclasses> on the metaclass and only allowing |
96 | you to assign a single superclass. |
97 | |
98 | The L<Moose::Policy::FollowPBP> policy changes the default behavior of |
99 | accessors to fit the recomendations found in Perl Best Practices. |
100 | |
101 | =head1 CAVEATS |
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102 | |
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103 | =head2 Always load Moose::Policy first. |
104 | |
105 | You B<must> put the following line of code: |
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106 | |
107 | use Moose::Policy 'My::Policy'; |
108 | |
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109 | before this line: |
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110 | |
111 | use Moose; |
112 | |
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113 | This is because Moose::Policy must be given the opportunity to set the |
114 | custom metaclass before Moose has set it's default metaclass. In fact, if |
115 | you try to set a Moose::Policy and there is a C<meta> method available, |
116 | not only will kittens die, but your program will too. |
117 | |
118 | =head2 Policys are class scoped |
119 | |
120 | You must repeat the policy for each class you want to us it. It is B<not> |
121 | inherited. This may change in the future, probably it will be a Moose::Policy |
122 | itself to allow Moose policys to be inherited. |
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123 | |
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124 | =head1 THE POLICY |
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125 | |
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126 | A Policy is set by passing C<Moose::Polocy::import()> a package name. This |
127 | package is then queried for what metaclasses it should use. The possible |
128 | metaclass values are: |
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129 | |
130 | =over |
131 | |
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132 | =item B<metaclass> |
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133 | |
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134 | This defaults to C<Moose::Meta::Class>. |
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135 | |
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136 | =item B<attribute_metaclass> |
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137 | |
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138 | =item B<instance_metaclass> |
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139 | |
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140 | =item B<method_metaclass> |
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141 | |
142 | =back |
143 | |
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144 | For examples of what a Policy actually looks like see the examples in |
145 | C<Moose::Policy::> and the test suite. More docs to come on this later (probably |
146 | a cookbook or something). |
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147 | |
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148 | =head1 FUTURE PLANS |
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149 | |
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150 | As I said above, this is the first release and it is by no means feature complete. |
151 | There are a number of thoughts on the future direction of this module. Here are |
152 | some random thoughts on that, in no particular order. |
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153 | |
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154 | =over 4 |
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155 | |
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156 | =item Make set of policy roles |
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157 | |
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158 | Roles are an excellent way to combine sets of behaviors together into one, and |
159 | custom metaclasses are actually better composed by roles then by inheritence. |
160 | The ideal situation is that this module will provide a set of roles which can be |
161 | used to compose you meta-policy with relative ease. |
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162 | |
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163 | =back |
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164 | |
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165 | =head1 BUGS |
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166 | |
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167 | All complex software has bugs lurking in it, and this module is no |
168 | exception. If you find a bug please either email me, or add the bug |
169 | to cpan-RT. |
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170 | |
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171 | =head1 AUTHOR |
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172 | |
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173 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
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174 | |
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175 | Eric Wilhelm E<lt>...E<gt> |
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176 | |
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177 | =head1 COPYRIGHT AND LICENSE |
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178 | |
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179 | Copyright 2006 by Infinity Interactive, Inc. |
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180 | |
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181 | L<http://www.iinteractive.com> |
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182 | |
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183 | This library is free software; you can redistribute it and/or modify |
184 | it under the same terms as Perl itself. |
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185 | |
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186 | =cut |
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187 | |