Class::MethodMaker::V1Compat - V1 compatibility code for C::MM

This class is for internal implementation only. It is not a public API.

Class::MethodMaker version 2 strives for backward-compatiblity with version 1 as far as possible. That is to say, classes built with version 1 should work with few if any changes. However, the calling conventions for building new classes are significantly different: this is necessary to achieve a greater consistency of arguments.

Version 2 takes all arguments within a single arrayref:

  use Class::MethodMaker
    [ scalar => 'a' ];

If arguments are presented as a list, then Class::MethodMaker assumes that this is a version 1 call, and acts accordingly. Version 1 arguments are passed and internally rephrased to version 2 arguments, and passed off to the version 2 engine. Thus, the majority of version 1 calls can be upgraded to version 2 merely by rephrasing. However, there are a number of behaviours that in version 1 that are internally inconsistent. These behaviours are mimicked in version 1 mode as far as possible, but are not reproducible in version 2 (to allow version 2 clients to rely on a more internally consistent interface).

The nearest equivalent to each 1 component (slot) available in version 2 is shown below using the indicated data-structures & options to create a component called CWa that mimicks the V1 component behaviour as closely as possible:

abstract

  use Class::MethodMaker
    [ abstract => 'a' ];

boolean

Boolean is available as a backwards compatiblity hack, but there is currently no V2 equivalent. It is likely that some replacement mechanism will be introduced in the future, but that it will be incompatible with the version 1 boolean.

code

  use Class::MethodMaker
    [ scalar => 'a' ];

Let's face it, the v1 store-if-it's-a-coderef-else-retrieve semantics are rather broken. How do you pass a coderef as argument to one of these? It is on the TODO list to recognize code as fundamental restricted type (analogous to INTEGER), which would add in a CW*_invoke method.

copy

  use Class::MethodMaker
    [ copy => 'a' ];

The v2 method is the same as v1.

counter

  use Class::MethodMaker
    [ scalar => [{-type => Class::MethodMaker::Constants::INTEGER}, 'a'] ];

copy

deep_copy

  use Class::MethodMaker
    [ copy => [ -deep => 'a' ] ];

get_concat

  use Class::MethodMaker
    [ scalar => [{ -store_cb => sub {
                                  defined $_[1] ? ( defined $_[3] ?
                                                    "$_[3] $_[1]" : $_[1] )
                                                : undef;
                                }
                 },
                 'a' ]
    ];

get_set

  use Class::MethodMaker
    [ scalar => 'a' ];

hash

  use Class::MethodMaker
    [ hash => 'a' ];

key_attrib

Although v1 calls will continue to work, this is not supported in v2.

key_with_create

Although v1 calls will continue to work, this is not supported in v2.

list

  use Class::MethodMaker
    [ list => 'a' ];

Note that the CW* method now sets the whole array if given arguments.

method

See CWcode.

new

  use Class::MethodMaker
    [ new => 'a' ];

new_hash_init

  use Class::MethodMaker
    [ new => [ -hash => 'a' ] ];

new_hash_with_init

  use Class::MethodMaker
    [ new => [ -hash => -init => 'a' ] ];

new_with_args

Although v1 calls will continue to work, this is not supported in v2, for it is a trivial application of CWnew_with_init.

new_with_init

  use Class::MethodMaker
    [ new => [ -init => 'a' ] ];

object

  use Class::MethodMaker
    [ scalar => [{ -type    => 'MyClass',
                   -forward => [qw/ method1 method2 /] }, 'a' ]
    ];

object_tie_hash

  use Class::MethodMaker
    [ hash => [{ -type      => 'MyClass',
                 -forward   => [qw/ method1 method2 /],
                 -tie_class => 'Tie::MyTie',
                 -tie_args  => [qw/ foo bar baz /],
               }, 'a' ]
    ];

object_tie_list

  use Class::MethodMaker
    [ array => [{ -type      => 'MyClass',
                  -forward   => [qw/ method1 method2 /],
                  -tie_class => 'Tie::MyTie',
                  -tie_args  => [qw/ foo bar baz /],
                }, 'a' ]
    ];

set_once

  use Class::MethodMaker
    [ scalar => [{ -store_cb => sub {
                                  die "Already stored $_[3]"
                                    if @_ > 3;
                                }
                 },
                 'a' ]
    ];

set_once_static

  use Class::MethodMaker
    [ scalar => [{ -store_cb => sub {
                                  die "Already stored $_[3]"
                                    if @_ > 3;
                                },
                   -static   => 1,
                 },
                 'a' ]
    ];

singleton

  use Class::MethodMaker
    [ new => [ -singleton => -hash => -init => 'a' ] ];

static_get_set

  use Class::MethodMaker
    [ scalar => [ -static => 'a' ], ];

static_hash

  use Class::MethodMaker
    [ hash => [ -static => 'a' ], ];

static_list

  use Class::MethodMaker
    [ list => [ -static => 'a' ], ];

tie_hash

  use Class::MethodMaker
    [ hash => [ { -tie_class => 'MyTie',
                  -tie_args  => [qw/ foo bar baz /],
                } => 'a' ], ];

tie_list

  use Class::MethodMaker
    [ array => [ { -tie_class => 'MyTie',
                   -tie_args  => [qw/ foo bar baz /],
                 } => 'a' ], ];

tie_scalar

  use Class::MethodMaker
    [ scalar => [ { -tie_class => 'MyTie',
                    -tie_args  => [qw/ foo bar baz /],
                  } => 'a' ], ];

The following version 1 component (slot) types are not currently supported in version 2:

grouped_fields

hash_of_lists

listed_attrib

struct

Email the development mailing list CWclass-mmaker-devel@lists.sourceforge.net.

Martyn J. Pearce

Copyright (c) 2003, 2004 Martyn J. Pearce. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.