Class::Observable Class::Observable is a Perl module that allows other classes and objects to respond to events in yours.
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Class::Observable Tags

Perl module event Perl classes event responses responses

Class::Observable Description

Class::Observable is a Perl module that allows other classes and objects to respond to events in yours. Class::Observable is a Perl module that allows other classes and objects to respond to events in yours.SYNOPSIS # Define an observable class package My::Object; use base qw( Class::Observable ); # Tell all classes/objects observing this object that a state-change # has occurred sub create { my ( $self ) = @_; eval { $self->_perform_create() }; if ( $@ ) { My::Exception->throw( "Error saving: $@" ); } $self->notify_observers(); } # Same thing, except make the type of change explicit and pass # arguments. sub edit { my ( $self ) = @_; my %old_values = $self->extract_values; eval { $self->_perform_edit() }; if ( $@ ) { My::Exception->throw( "Error saving: $@" ); } $self->notify_observers( 'edit', old_values => %old_values ); } # Define an observer package My::Observer; sub update { my ( $class, $object, $action ) = @_; unless ( $action ) { warn "Cannot operation on without action"; return; } $class->_on_save( $object ) if ( $action eq 'save' ); $class->_on_update( $object ) if ( $action eq 'update' ); } # Register the observer class with all instances of the observable # class My::Object->add_observer( 'My::Observer' ); # Register the observer class with a single instance of the # observable class my $object = My::Object->new( 'foo' ); $object->add_observer( 'My::Observer' ); # Register an observer object the same way my $observer = My::Observer->new( 'bar' ); My::Object->add_observer( $observer ); my $object = My::Object->new( 'foo' ); $object->add_observer( $observer ); # Register an observer using a subroutine sub catch_observation { ... } My::Object->add_observer( &catch_observation ); my $object = My::Object->new( 'foo' ); $object->add_observer( &catch_observation ); # Define the observable class as a parent and allow the observers to # be used by the child package My::Parent; use strict; use base qw( Class::Observable ); sub prepare_for_bed { my ( $self ) = @_; $self->notify_observers( 'prepare_for_bed' ); } sub brush_teeth { my ( $self ) = @_; $self->_brush_teeth( time => 45 ); $self->_floss_teeth( time => 30 ); $self->_gargle( time => 30 ); } sub wash_face { ... } package My::Child; use strict; use base qw( My::Parent ); sub brush_teeth { my ( $self ) = @_; $self->_wet_toothbrush(); } sub wash_face { return } # Create a class-based observer package My::ParentRules; sub update { my ( $item, $action ) = @_; if ( $action eq 'prepare_for_bed' ) { $item->brush_teeth; $item->wash_face; } } My::Parent->add_observer( __PACKAGE__ ); $parent->prepare_for_bed # brush, floss, gargle, and wash face $child->prepare_for_bed # pretend to brush, pretend to wash face Requirements: · Perl

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