man Class::C3::Adopt::NEXT (3): make NEXT suck less

VERSION

version 0.14

SYNOPSIS

package MyApp::Plugin::FooBar;
#use NEXT;
use Class::C3::Adopt::NEXT;
# or 'use Class::C3::Adopt::NEXT -no_warn;' to suppress warnings
# Or use warnings::register
# no warnings 'Class::C3::Adopt::NEXT';
# Or suppress warnings in a set of modules from one place
# no Class::C3::Adopt::NEXT qw/ Module1 Module2 Module3 /;
# Or suppress using a regex
# no Class::C3::Adopt::NEXT qr/^Module\d$/;
sub a_method {
my ($self) = @_;
# Do some stuff
# Re-dispatch method
# Note that this will generate a warning the _first_ time the package
# uses NEXT unless you un comment the 'no warnings' line above.
$self->NEXT::method();
}

DESCRIPTION

NEXT was a good solution a few years ago, but isn't any more. It's slow, and the order in which it re-dispatches methods appears random at times. It also encourages bad programming practices, as you end up with code to re-dispatch methods when all you really wanted to do was run some code before or after a method fired.

However, if you have a large application, then weaning yourself off "NEXT" isn't easy.

This module is intended as a drop-in replacement for NEXT, supporting the same interface, but using Class::C3 to do the hard work. You can then write new code without "NEXT", and migrate individual source files to use "Class::C3" or method modifiers as appropriate, at whatever pace you're comfortable with.

WARNINGS

This module will warn once for each package using NEXT. It uses warnings::register, and so can be disabled like by adding "no warnings 'Class::C3::Adopt::NEXT';" to each package which generates a warning, or adding "use Class::C3::Adopt::NEXT -no_warn;", or disable multiple modules at once by saying:

    no Class::C3::Adopt::NEXT qw/ Module1 Module2 Module3 /;

somewhere before the warnings are first triggered. You can also setup entire name spaces of modules which will not warn using a regex, e.g.

    no Class::C3::Adopt::NEXT qr/^Module\d$/;

MIGRATING

Current code using NEXT

You add "use MRO::Compat" to the top of a package as you start converting it, and gradually replace your calls to "NEXT::method()" with "maybe::next::method()", and calls to "NEXT::ACTUAL::method()" with "next::method()".

Example:

    sub yourmethod {
        my $self = shift;
        # $self->NEXT::yourmethod(@_); becomes
        $self->maybe::next::method();
    }
    sub othermethod {
        my $self = shift;
        # $self->NEXT::ACTUAL::yourmethodname(); becomes
        $self->next::method();
    }

On systems with Class::C3::XS present, this will automatically be used to speed up method re-dispatch. If you are running perl version 5.9.5 or greater then the C3 method resolution algorithm is included in perl. Correct use of MRO::Compat as shown above allows your code to be seamlessly forward and backwards compatible, taking advantage of native versions if available, but falling back to using pure perl "Class::C3".

Writing new code

Use Moose and make all of your plugins Moose::Roles, then use method modifiers to wrap methods.

Example:

    package MyApp::Role::FooBar;
    use Moose::Role;
    before 'a_method' => sub {
        my ($self) = @_;
        # Do some stuff
    };
    around 'a_method' => sub {
        my $orig = shift;
        my $self = shift;
        # Do some stuff before
        my $ret = $self->$orig(@_); # Run wrapped method (or not!)
        # Do some stuff after
        return $ret;
    };
    package MyApp;
    use Moose;
    with 'MyApp::Role::FooBar';

CAVEATS

There are some inheritance hierarchies that it is possible to create which cannot be resolved to a simple C3 hierarchy. In that case, this module will fall back to using "NEXT". In this case a warning will be emitted.

Because calculating the method resolution order of every class every time "->NEXT::foo" is used from within it is too expensive, runtime manipulations of @ISA are prohibited.

FUNCTIONS

This module replaces "NEXT::AUTOLOAD" with its own version. If warnings are enabled then a warning will be emitted on the first use of "NEXT" by each package.

AUTHORS

Florian Ragwitz <[email protected]>
Tomas Doran <[email protected]>

CONTRIBUTOR

Karen Etheridge <[email protected]>

COPYRIGHT AND LICENSE

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.