NAME
Homer - Simple prototype-based object system
SYNOPSIS
use Homer;
# create a prototype object
my $person = Homer->new(
first_name => 'Generic',
last_name => 'Person',
say_hi => sub {
my $self = shift;
print "Hi, my name is ", $self->first_name, ' ', $self->last_name, "\n";
}
);
# create a new object based on it
my $homer = $person->extend(
first_name => 'Homer',
last_name => 'Simpson'
);
$homer->say_hi; # prints 'Hi, my name is Homer Simpson'
# let's extend even more
my $bart = $homer->extend(
first_name => 'Bart',
father => sub { print "My father's name is ", $_[0]->prot->first_name, "\n" }
);
$bart->say_hi; # prints 'Hi, my name is Bart Simpson'
$bart->father; # prints "My father's name is Homer"
DESCRIPTION
"Homer" is a very simple prototype-based object system, similar to
JavaScript. In a prototype based object system there are no classes.
Objects are either directly created with some attributes and methods, or
cloned from existing objects, in which case the object being cloned
becomes the prototype of the new object. The new object inherits all
attributes and methods from the prototype. Attributes and methods can be
overridden, and new ones can be added. The new object can be cloned as
well, becoming the prototype of yet another new object, thus creating a
possibly endless chain of prototypes.
Prototype-based objects can be very powerful and useful in certain
cases. They can provide a quick way of solving problems. Plus, sometimes
you just really need an object, but don't need a class. I like to think
of prototype-based OO versus class-based OO as being similar to
schema-less database systems versus relational database systems.
"Homer" is a quick and dirty implementation of such a system in Perl. As
Perl is a class-based language, this is merely a hack. When an object is
created, "Homer" creates a specific class just for it behind the scenes.
When an object is cloned, a new class is created for the clone, with the
parent object's class pushed to the new one's @ISA variable, thus
providing inheritance.
I can't say this implementation is particularly smart or efficient, but
it gives me what I need and is very lightweight ("Homer" has no non-core
dependencies). If you need a more robust solution, Class::Prototyped
might fit your need.
HOMER AT A GLANCE
* Prototypes are created by calling "new()" on the "Homer" class with
a hash, holding attributes and methods:
my $prototype = Homer->new(
attr1 => 'value1',
attr2 => 'value2',
meth1 => sub { print "meth1" }
);
$prototype->attr1; # value1
$prototype->attr2; # value2
$prototype->meth1; # prints "meth1"
* A list of all pure-attributes of an object (i.e. not methods) can be
received by calling "attributes()" on the object.
$prototype->attributes; # ('attr1', 'attr2')
* Every object created by Homer can be cloned using "extend( %attrs
)". The hash can contain new attributes and methods, and can
override existing ones.
my $clone = $prototype->extend(
attr2 => 'value3',
meth2 => sub { print "meth2" }
);
$clone->attr1; # value1
$clone->attr2; # value3
$clone->meth1; # prints "meth1"
$clone->meth2; # prints "meth2"
* Objects based on a prototype can refer to their prototype using the
"prot()" method:
$clone->prot->attr2; # value2
* All attributes are read-write:
$clone->attr1('value4');
$clone->attr1; # value4
$clone->prot->attr1; # still value1
* New methods can be added to an object after its construction. If the
object is a prototype of other objects, they will immediately
receive the new methods too.
$prototype->add_method('meth3' => sub { print "meth3" });
$clone->can('meth3'); # true
* New attributes can't be added after construction (for now).
* Cloned objects can be cloned too, creating a chain of prototypes:
my $clone2 = $clone->extend;
my $clone3 = $clone2->extend;
$clone3->prot->prot->prot; # the original $prototype
CONSTRUCTOR
new( [ %attrs ] )
Creates a new prototype object with the provided attributes and methods
(if any).
CONFIGURATION AND ENVIRONMENT
"Homer" requires no configuration files or environment variables.
DEPENDENCIES
None other than Carp.
BUGS AND LIMITATIONS
Please report any bugs or feature requests to "bug-Homer@rt.cpan.org",
or through the web interface at
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc Homer
You can also look for information at:
* RT: CPAN's request tracker
* AnnoCPAN: Annotated CPAN documentation
* CPAN Ratings
* Search CPAN
AUTHOR
Ido Perlmuter <ido@ido50.net>
LICENSE AND COPYRIGHT
Copyright 2017 Ido Perlmuter
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.