1 | package Mojo::EventEmitter;
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2 | use Mojo::Base -base;
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3 |
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4 | use Scalar::Util qw(blessed weaken);
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5 |
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6 | use constant DEBUG => $ENV{MOJO_EVENTEMITTER_DEBUG} || 0;
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7 |
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8 | sub catch { $_[0]->on(error => $_[1]) and return $_[0] }
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9 |
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10 | sub emit {
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11 | my ($self, $name) = (shift, shift);
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12 |
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13 | if (my $s = $self->{events}{$name}) {
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14 | warn "-- Emit $name in @{[blessed $self]} (@{[scalar @$s]})\n" if DEBUG;
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15 | for my $cb (@$s) { $self->$cb(@_) }
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16 | }
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17 | else {
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18 | warn "-- Emit $name in @{[blessed $self]} (0)\n" if DEBUG;
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19 | die "@{[blessed $self]}: $_[0]" if $name eq 'error';
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20 | }
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21 |
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22 | return $self;
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23 | }
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24 |
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25 | sub has_subscribers { !!shift->{events}{shift()} }
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26 |
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27 | sub on { push @{$_[0]{events}{$_[1]}}, $_[2] and return $_[2] }
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28 |
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29 | sub once {
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30 | my ($self, $name, $cb) = @_;
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31 |
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32 | weaken $self;
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33 | my $wrapper;
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34 | $wrapper = sub {
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35 | $self->unsubscribe($name => $wrapper);
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36 | $cb->(@_);
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37 | };
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38 | $self->on($name => $wrapper);
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39 | weaken $wrapper;
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40 |
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41 | return $wrapper;
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42 | }
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43 |
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44 | sub subscribers { shift->{events}{shift()} ||= [] }
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45 |
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46 | sub unsubscribe {
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47 | my ($self, $name, $cb) = @_;
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48 |
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49 | # One
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50 | if ($cb) {
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51 | $self->{events}{$name} = [grep { $cb ne $_ } @{$self->{events}{$name}}];
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52 | delete $self->{events}{$name} unless @{$self->{events}{$name}};
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53 | }
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54 |
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55 | # All
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56 | else { delete $self->{events}{$name} }
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57 |
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58 | return $self;
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59 | }
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60 |
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61 | 1;
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62 |
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63 | =encoding utf8
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64 |
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65 | =head1 NAME
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66 |
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67 | Mojo::EventEmitter - Event emitter base class
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68 |
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69 | =head1 SYNOPSIS
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70 |
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71 | package Cat;
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72 | use Mojo::Base 'Mojo::EventEmitter';
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73 |
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74 | # Emit events
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75 | sub poke {
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76 | my $self = shift;
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77 | $self->emit(roar => 3);
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78 | }
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79 |
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80 | package main;
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81 |
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82 | # Subscribe to events
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83 | my $tiger = Cat->new;
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84 | $tiger->on(roar => sub {
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85 | my ($tiger, $times) = @_;
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86 | say 'RAWR!' for 1 .. $times;
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87 | });
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88 | $tiger->poke;
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89 |
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90 | =head1 DESCRIPTION
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91 |
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92 | L<Mojo::EventEmitter> is a simple base class for event emitting objects.
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93 |
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94 | =head1 EVENTS
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95 |
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96 | L<Mojo::EventEmitter> can emit the following events.
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97 |
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98 | =head2 error
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99 |
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100 | $e->on(error => sub {
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101 | my ($e, $err) = @_;
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102 | ...
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103 | });
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104 |
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105 | This is a special event for errors, it will not be emitted directly by this
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106 | class, but is fatal if unhandled. Subclasses may choose to emit it, but are not
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107 | required to do so.
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108 |
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109 | $e->on(error => sub {
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110 | my ($e, $err) = @_;
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111 | say "This looks bad: $err";
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112 | });
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113 |
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114 | =head1 METHODS
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115 |
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116 | L<Mojo::EventEmitter> inherits all methods from L<Mojo::Base> and implements
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117 | the following new ones.
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118 |
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119 | =head2 catch
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120 |
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121 | $e = $e->catch(sub {...});
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122 |
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123 | Subscribe to L</"error"> event.
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124 |
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125 | # Longer version
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126 | $e->on(error => sub {...});
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127 |
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128 | =head2 emit
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129 |
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130 | $e = $e->emit('foo');
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131 | $e = $e->emit('foo', 123);
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132 |
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133 | Emit event.
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134 |
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135 | =head2 has_subscribers
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136 |
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137 | my $bool = $e->has_subscribers('foo');
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138 |
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139 | Check if event has subscribers.
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140 |
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141 | =head2 on
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142 |
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143 | my $cb = $e->on(foo => sub {...});
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144 |
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145 | Subscribe to event.
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146 |
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147 | $e->on(foo => sub {
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148 | my ($e, @args) = @_;
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149 | ...
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150 | });
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151 |
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152 | =head2 once
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153 |
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154 | my $cb = $e->once(foo => sub {...});
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155 |
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156 | Subscribe to event and unsubscribe again after it has been emitted once.
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157 |
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158 | $e->once(foo => sub {
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159 | my ($e, @args) = @_;
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160 | ...
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161 | });
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162 |
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163 | =head2 subscribers
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164 |
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165 | my $subscribers = $e->subscribers('foo');
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166 |
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167 | All subscribers for event.
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168 |
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169 | # Unsubscribe last subscriber
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170 | $e->unsubscribe(foo => $e->subscribers('foo')->[-1]);
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171 |
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172 | # Change order of subscribers
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173 | @{$e->subscribers('foo')} = reverse @{$e->subscribers('foo')};
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174 |
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175 | =head2 unsubscribe
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176 |
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177 | $e = $e->unsubscribe('foo');
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178 | $e = $e->unsubscribe(foo => $cb);
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179 |
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180 | Unsubscribe from event.
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181 |
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182 | =head1 DEBUGGING
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183 |
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184 | You can set the C<MOJO_EVENTEMITTER_DEBUG> environment variable to get some
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185 | advanced diagnostics information printed to C<STDERR>.
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186 |
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187 | MOJO_EVENTEMITTER_DEBUG=1
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188 |
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189 | =head1 SEE ALSO
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190 |
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191 | L<Mojolicious>, L<Mojolicious::Guides>, L<https://mojolicious.org>.
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192 |
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193 | =cut
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