Author image Marvin Humphrey
and 1 contributors


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 {
            # 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:

  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.



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 {
            # 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.



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.



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


    BEGIN {
            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 2005-2009 Marvin Humphrey


See KinoSearch version 0.165.