KinoSearch::Util::Class - class building utility |
KinoSearch::Util::Class - class building utility
This is a private class and the interface may change radically and without warning. Do not use it on its own.
package KinoSearch::SomePackage::SomeClass; use base qw( KinoSearch::Util::Class ); BEGIN { __PACKAGE__->init_instance_vars( # constructor params / members foo => undef, bar => {},
# members baz => {}, ); }
KinoSearch::Util::Class is a class-building utility a la Class::Accessor, Class::Meta, etc. It provides four main services:
The %instance_vars hash, which is always a package global, serves as a template for the creation of a hash-based object. It is built up from all the %instance_vars hashes in the module's parent classes, using init_instance_vars().
Key-value pairs in an %instance_vars hash are labeled as ``constructor params'' and/or ``members''. Items which are labeled as constructor params can be used as arguments to new().
BEGIN { __PACKAGE__->init_instance_vars( # constructor params / members foo => undef, bar => {}, # members baz => '', ); } # ok: specifies foo, uses default for bar, derives baz my $object = __PACKAGE__->new( foo => $foo );
# not ok: baz isn't a constructor param my $object = __PACKAGE__->new( baz => $baz );
# ok if a parent class defines boffo as a constructor param my $object = __PACKAGE__->new( foo => $foo, boffo => $boffo, );
%instance_vars may contain hashrefs and array-refs, as Clone's
clone()
method is used to produce a deep copy.
init_instance_vars()
must be called from within a BEGIN block and before any
use
directives load a child class -- if children are born before their
parents, inheritance gets screwed up.
A generic constructor with basic argument checking. new()
expects hash-style
labeled parameters; the label names must be present in the %instance_vars
hash, or it will croak().
After verifying the labeled parameters, new()
creates a deep clone of
%instance_vars, and merges in the labeled arguments. It then calls
$self->init_instance()
before returning the blessed reference.
$self->init_instance();
Perform customized initialization routine. By default, this is a no-op.
BEGIN { __PACKAGE__->init_instance_vars( a_safe_variable_name_that_wont_clash => 1, freep_warble => undef, ); }
Package method only. Creates a package global %instance_vars hash in the passed in package which consists of the passed in arguments plus all the key-value pairs in the parent class's %instance_vars hash.
# create get_foo(), set_foo(), get_bar(), set_bar() in __PACKAGE__ BEGIN { __PACKAGE__->ready_get_set(qw( foo bar )) };
Mass manufacture getters and setters. The setters do not return a meaningful value.
sub an_abstract_method { shift->abstract_death } sub an_unimplemented_method { shift->unimplemented_death } sub maybe_someday { shift->todo_death }
These are just different ways to die(), and are of little interest until your particular application comes face to face with one of them.
abstract_death indicates that a method must be defined in a subclass.
unimplemented_death indicates a feature/function that will probably not be implemented. Typically, this would appear for a sub that a developer intimately familiar with Lucene would expect to find.
todo_death indicates a feature that might get implemented someday.
Copyright 2005-2006 Marvin Humphrey
See KinoSearch version 0.15.
KinoSearch::Util::Class - class building utility |