Toby Inkster > Object-Stash-0.005 > Object::Stash

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Module Version: 0.005   Source  

NAME ^

Object::Stash - provides a Catalyst-like "stash" method for your class

SYNOPSIS ^

 {
   package MyClass;
   use Object::New;
   use Object::Stash 'data';
 }
 
 use feature 'say';
 use Data::Printer qw(p);
 my $obj = MyClass->new;
 p $obj->data;                     # an empty hashref
 $obj->data(foo => 1, bar => 2);   # sets values in the 'data' stash
 $obj->data({foo => 1, bar => 2}); # same
 p $obj->data;                     # hashref with keys 'foo', 'bar'
 say $obj->data->{foo};            # says '1'
 
 # Retrieve multiple values
 my @values = $obj->data(['foo', 'bar']);
 say $values[0];                   # says '1'
 say $values[1];                   # says '2'
 
 # Or in scalar context
 my $values = $obj->data(['foo', 'bar']);
 say $values->[0];                 # says '1'
 say $values->[1];                 # says '2'

DESCRIPTION ^

The Catalyst context object has a method called stash, that provides a hashref for storing arbitrary data associated with the object. This is arguably a little hackish - the proper solution might be to create a slot for each piece of information you wish to store, with appropriate accessor methods. But often hackish will do.

(And there are non-hackish ways of using Object::Stash. Take a look at Web::Magic which uses a private stash - named with a leading underscore - and provides public methods for accessing various things stored inside it.)

Object::Stash sets up one or more stash methods for your class. How these methods are named depends on how Object::Stash is imported. Object::Stash is a role, like Object::New or Object::ID. This means you import it, but don't inherit from it.

Default method name

 package MyClass;
 use Object::Stash;

Creates a single method for MyClass objects. The method is called "stash".

Custom method name

 package MyClass;
 use Object::Stash 'data';

Creates a single method for MyClass objects. The method is called "data".

Multiple methods

 package MyClass;
 use Object::Stash qw/important trivial/;

Creates two stashes for MyClass objects, called "important" and "trivial". Adding data to one stash will not affect the other stash. You could alternatively write:

 package MyClass;
 use Object::Stash 'important'
 use Object::Stash 'trivial';

Adding stashes to other classes

 package MyClass;
 use Object::Stash -package => 'YourClass', 'my_stash';

Creates a stash called "my_stash" for YourClass objects.

Utility Functions

Object::Stash->is_stash( $coderef )

Returns true if the method is a stash. For example:

  my $method = MyClass->can('trivial');
  if (Object::Stash->is_stash($method))
  {
    $method->(foo => 1, bar => 2);
  }

Can also be called as Object::Stash::is_stash($coderef).

Stash Storage

Stashes are stored "inside-out", meaning that they will work not only with objects which are blessed hashrefs, but also with any other type of object internals. Dumping your object with Data::Dumper or similar will not display the contents of the stashes. (A future release of this module may introduce other storage options, but the current inside-out storage is likely to remain the default.)

Thanks to Hash::FieldHash, an object's stashes should get automatically garbage collected once the object itself is destroyed, unless you've maintained your own references to the stashes.

Stash Objects

While stashes are usually hashrefs, there is also an option to make stashes themselves blessed objects. It's best to illustrate this with an example

 {
   package MyClass;
   use Object::New;
   use Object::Stash 'data', -type => 'object';
 }
 
 # All this stuff from SYNOPSIS still works...
 use feature 'say';
 use Data::Printer qw(p);
 my $obj = MyClass->new;
 p $obj->data;                     # an empty hashref
 $obj->data(foo => 1, bar => 2);   # sets values in the 'data' stash
 $obj->data({foo => 1, bar => 2}); # same
 say $obj->data->{foo};            # says '1'
 
 my @values = $obj->data(['foo', 'bar']);
 say $values[0];                   # says '1'
 say $values[1];                   # says '2'
 
 my $values = $obj->data(['foo', 'bar']);
 say $values->[0];                 # says '1'
 say $values->[1];                 # says '2'
 
 # But now you can retrieve data using accessor methods...
 say $obj->data->foo;              # says '1'
 
 # The accessors work as not just getters, but setters...
 $obj->data->foo(99);
 
 # The accessors can be treated as lvalues...
 $obj->data->foo = 100;
 $obj->data->foo++;
 
 # Cool, huh?
 say $obj->data->{foo};            # says '101'
 
 # In case you were wondering...
 say ref $obj->data;               # says 'Object::Stash::data'

BUGS ^

Please report any bugs to http://rt.cpan.org/Dist/Display.html?Queue=Object-Stash.

SEE ALSO ^

Object::New, Object::ID.

AUTHOR ^

Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE ^

This software is copyright (c) 2011 by Toby Inkster.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTIES ^

THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

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