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1 | package MooseX::Singleton::Role::Meta::Class; |
2 | use Moose::Role; |
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3 | use MooseX::Singleton::Role::Meta::Instance; |
4 | use MooseX::Singleton::Role::Meta::Method::Constructor; |
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5 | |
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6 | our $VERSION = '0.25'; |
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7 | $VERSION = eval $VERSION; |
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8 | |
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9 | sub existing_singleton { |
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10 | my ($class) = @_; |
11 | my $pkg = $class->name; |
12 | |
13 | no strict 'refs'; |
14 | |
15 | # create exactly one instance |
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16 | if ( defined ${"$pkg\::singleton"} ) { |
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17 | return ${"$pkg\::singleton"}; |
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18 | } |
19 | |
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20 | return; |
21 | } |
22 | |
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23 | sub clear_singleton { |
24 | my ($class) = @_; |
25 | my $pkg = $class->name; |
26 | no strict 'refs'; |
27 | undef ${"$pkg\::singleton"}; |
28 | } |
29 | |
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30 | override _construct_instance => sub { |
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31 | my ($class) = @_; |
32 | |
33 | # create exactly one instance |
34 | my $existing = $class->existing_singleton; |
35 | return $existing if $existing; |
36 | |
37 | my $pkg = $class->name; |
38 | no strict 'refs'; |
39 | return ${"$pkg\::singleton"} = super; |
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40 | }; |
41 | |
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42 | if ( $Moose::VERSION >= 1.9900 ) { |
43 | override _inline_params => sub { |
44 | my $self = shift; |
45 | |
46 | return |
47 | 'my $existing = do {', |
48 | 'no strict "refs";', |
49 | 'no warnings "once";', |
50 | '\${"$class\::singleton"};', |
51 | '};', |
52 | 'return ${$existing} if ${$existing};', |
53 | super(); |
54 | }; |
55 | |
56 | override _inline_extra_init => sub { |
57 | my $self = shift; |
58 | |
59 | return '${$existing} = $instance;'; |
60 | }; |
61 | } |
62 | |
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63 | no Moose::Role; |
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64 | |
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65 | 1; |
66 | |
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67 | __END__ |
68 | |
69 | =pod |
70 | |
71 | =head1 NAME |
72 | |
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73 | MooseX::Singleton::Role::Meta::Class - Metaclass role for MooseX::Singleton |
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74 | |
75 | =head1 DESCRIPTION |
76 | |
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77 | This metaclass role makes sure that there is only ever one instance of an |
78 | object for a singleton class. The first call to C<construct_instance> is run |
79 | normally (and then cached). Subsequent calls will return the cached version. |
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80 | |
81 | =cut |
82 | |