/ 
KinoSearch-0.16
River stage two • 9 direct dependents • 10 total dependents
/ KinoSearch::Util::Class

NAME

KinoSearch::Util::Class - class building utility

PRIVATE CLASS

This is a private class and the interface may change radically and without warning. Do not use it on its own.

SYNOPSIS

package KinoSearch::SomePackage::SomeClass;
use base qw( KinoSearch::Util::Class );

BEGIN {
    __PACKAGE__->init_instance_vars(
        # constructor params / members
        foo => undef,
        bar => {},

        # members
        baz => {},
    );
}

DESCRIPTION

KinoSearch::Util::Class is a class-building utility a la Class::Accessor, Class::Meta, etc. It provides four main services:

  1. A mechanism for inheriting instance variable declarations.

  2. A constructor with basic argument checking.

  3. Manufacturing of get_xxxx and set_xxxx methods.

  4. Convenience methods which help in defining abstract classes.

VARIABLES

%instance_vars

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 => 10,
        # 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 only contain scalar values, as the defaults are merged into the object using a shallow 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.

METHODS

new

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() merges %instance_vars and @_ into a new object. It then calls $self->init_instance() before returning the blessed reference.

init_instance

$self->init_instance();

Perform customized initialization routine. By default, this is a no-op.

init_instance_vars

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.

ready_get_set ready_get ready_set

# 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.

abstract_death unimplemented_death todo_death

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

Copyright 2005-2006 Marvin Humphrey

LICENSE, DISCLAIMER, BUGS, etc.

See KinoSearch version 0.16.