table of contents
Class::C3::Adopt::NEXT(3pm) | User Contributed Perl Documentation | Class::C3::Adopt::NEXT(3pm) |
NAME¶
Class::C3::Adopt::NEXT - 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.
SEE ALSO¶
MRO::Compat and Class::C3 for method re-dispatch and Moose for method modifiers and roles.
NEXT for documentation on the functionality you'll be removing.
AUTHORS¶
- Florian Ragwitz <rafl@debian.org>
- Tomas Doran <bobtfish@bobtfish.net>
CONTRIBUTOR¶
Karen Etheridge <ether@cpan.org>
COPYRIGHT AND LICENSE¶
This software is copyright (c) 2015 by Florian Ragwitz.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
2015-06-07 | perl v5.40.0 |