forgot_other_usrname has asked for the wisdom of the Perl Monks concerning the following question:
I'm in need of "runtime decorators". That is, a class whose constructor is to take an instance of either the base class or a separate "runtime decorator" and add functionality to it. I don't know ahead of time what the type of the object will be.
Here's an extremely contrived example of what I want to do (this strategy makes sense in the actual problem domain).
UPDATE: This is getting closer to what I want, but it still adds to the class rather than the object
Then I could use it like followspackage Base; sub new { my $package = shift; my $id = shift; return bless { id => $id, }, $package; } sub id { my ($self, $id) = @_; $self->{id} = $id if defined $id; return $self->{id}; } 1; package NameDecorator; sub new { my $package = shift; my $base_or_decorated = shift; my $self = $base_or_decorated->new(@_); $self->{name} = undef; return $self->{name}; } sub name { my ($self, $name) = @_; $self->{name} = $name if defined $name; return $self->{name}; } 1; ...do the same for an AgeDecorator
I need the flexibility to be able to chain decorators together and still have available to methods added from the decorator before it. Is there a name for what I'm trying to do and can this be done easily without the help of a module or is there a module which can help me achieve this?use Base; use NameDecorator; use AgeDecorator; my $decorated = AgeDecorator->new(NameDecorator->new(Base->new('id1')) +); $decorated->name('Edith'); $decorated->age(93);
UPDATE: This is getting closer to what I want, but it still adds to the class rather than the object
package NameProto; use strict; use base qw(Base::Decorator); sub new { my $self = shift->SUPER::new(@_); $self->{age} = 0; no strict 'refs'; my $package = ref($self->{base}); *{$package . '::name'} = sub { my ($self, $name) = @_; $self->{name} = $name if defined $name; return $self->{name}; }; return bless $self, $package; } sub name { return shift->{base}->name(@_); } 1;
|
---|
Replies are listed 'Best First'. | |
---|---|
Re: Adding a method to an existing object
by chromatic (Archbishop) on Feb 13, 2012 at 02:50 UTC | |
by phaylon (Curate) on Feb 17, 2012 at 19:06 UTC | |
by chromatic (Archbishop) on Feb 17, 2012 at 19:20 UTC | |
Re: Adding a method to an existing object
by moritz (Cardinal) on Feb 13, 2012 at 07:15 UTC | |
Re: Adding a method to an existing object
by JavaFan (Canon) on Feb 13, 2012 at 10:08 UTC | |
Re: Adding a method to an existing object
by draegtun (Scribe) on Feb 17, 2012 at 16:56 UTC |
Back to
Seekers of Perl Wisdom