=pod

=head1 NAME

Object::By::Hash - minimalistic constructors for hash based objects

=head1 SYNOPSIS

	package some_package;
	use parent qw(Object::By::Hash);

	sub _constructor {
		my ($this, ...) = @_;
		$this->{'something'} = data of attribute;
		...
		return;
	}

	package main;
	use some_package;
	some_package->constructor(...);

=head1 DESCRIPTION

Object::By::Hash provides generic constructors for OO programming, which are tailored to an actual class via a method called _constructor. A generic constructor creates the reference from various sources, blesses, tailors, locks, and finally returns it. A small advantage at a small price of 50 lines of Perl code.

=head1 METHOD REFERENCE (API)

The design goal was a simple and robust API with a straightforward implementation, respecting all limitations of Perl 5.

=over 8

=item $class->constructor or class->constructor

A generic constructor for objects of the class. If the method _constructor is defined, calls _constructor and forwards any arguments to it. The data structure is locked afterwards.

=item $class->prototype_constructor or class->prototype_constructor

Prototype means, the object only carries a class and no data. Otherwise like class->constructor.

=item $old_object->sibling_constructor

Takes the class of $old_object to create an object of the same class. Otherwise works like class->constructor.

=item $old_object->clone_constructor

Takes the class of $old_object to create an object of the same class and the same data. Does not call _constructor, but copies the first level of the object's data structure. To leave no doubt: no deep copy is performed.

=back

For a way to use partial class names for object construction, see wild_construct from Package::Aspect::Wild_Class.


=head1 SUPPORTING CLASSES

These have no documentation of their own. These should come before Object::By::Hash in order to override any default methods.

=over 8

=item Object::By::Hash_Accessor

Provides the generic methods _get, _set and _get_or_set.

=item Object::By::Hash_Clone_Recursive

Provides a version of clone_constructor, which recursively calls the method on any contained objects.

=back


=head1 KNOWN BUGS AND LIMITATIONS

There are no tests.

There are numerous far more advanced approaches for generic constructors available on CPAN.

This module has been developed for the specific needs of FReDI and the Mica Environment. It is used by Mica, HTTP::Fools_Gold, Package::Aspect, Text::Placeholder and Object::Episode.


=head1 AUTHOR

Winfried Trumper E<lt>pub+perl(a)wt.tuxomania.netE<gt>

=head1 COPYRIGHT AND LICENSE

Copyright (C) 2011,2012 Winfried Trumper

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

=cut