MRO::Compat - mro::* interface compatibility for Perls < 5.9.5
package PPP; use base qw/Exporter/;
package X; use base qw/PPP/;
package Y; use base qw/PPP/;
package Z; use base qw/PPP/;
package FooClass; use base qw/X Y Z/;
package main;
use MRO::Compat;
my $linear = mro::get_linear_isa('FooClass');
print join(q{, }, @$linear);
# Prints: FooClass, X, PPP, Exporter, Y, Z
The ``mro'' namespace provides several utilities for dealing
with method resolution order and method caching in general
in Perl 5.9.5 and higher.
This module provides those interfaces for
earlier versions of Perl (back to 5.6.0 anyways).
It is a harmless no-op to use this module on 5.9.5+. That
is to say, code which properly uses the MRO::Compat manpage will work
unmodified on both older Perls and 5.9.5+.
If you're writing a piece of software that would like to use
the parts of 5.9.5+'s mro:: interfaces that are supported
here, and you want compatibility with older Perls, this
is the module for you.
Some parts of this code will work better and/or faster with
the Class::C3::XS manpage installed (which is an optional prereq
of the Class::C3 manpage, which is in turn a prereq of this
package), but it's not a requirement.
This module never exports any functions. All calls must
be fully qualified with the mro:: prefix.
The interface documentation here serves only as a quick
reference of what the function basically does, and what
differences between the MRO::Compat manpage and 5.9.5+ one should
look out for. The main docs in 5.9.5's mro are the real
interface docs, and contain a lot of other useful information.
Returns an arrayref which is the linearized ``ISA'' of the given class.
Uses whichever MRO is currently in effect for that class by default,
or the given MRO (either c3 or dfs if specified as $type).
The linearized ISA of a class is a single ordered list of all of the
classes that would be visited in the process of resolving a method
on the given class, starting with itself. It does not include any
duplicate entries.
Note that UNIVERSAL (and any members of UNIVERSAL's MRO) are not
part of the MRO of a class, even though all classes implicitly inherit
methods from UNIVERSAL and its parents.
This allows the use mro 'dfs' and
use mro 'c3' syntaxes, providing you
use MRO::Compat first. Please see the
USING C3 section for additional details.
Sets the mro of $classname to one of the types
dfs or c3. Please see the USING C3
section for additional details.
Returns the MRO of the given class (either c3 or dfs).
It considers any Class::C3-using class to have C3 MRO
even before the Class::C3::initialize() manpage is called.
Returns an arrayref of classes who are subclasses of the
given classname. In other words, classes in whose @ISA
hierarchy we appear, no matter how indirectly.
This is much slower on pre-5.9.5 Perls with MRO::Compat
than it is on 5.9.5+, as it has to search the entire
package namespace.
Returns a boolean status indicating whether or not
the given classname is either UNIVERSAL itself,
or one of UNIVERSAL's parents by @ISA inheritance.
Any class for which this function returns true is
``universal'' in the sense that all classes potentially
inherit methods from it.
Increments PL_sub_generation, which invalidates method
caching in all packages.
Please note that this is rarely necessary, unless you are
dealing with a situation which is known to confuse Perl's
method caching.
Invalidates the method cache of any classes dependent on the
given class. In the MRO::Compat manpage on pre-5.9.5 Perls, this is
an alias for mro::invalidate_all_method_caches above, as
pre-5.9.5 Perls have no other way to do this. It will still
enforce the requirement that you pass it a classname, for
compatibility.
Please note that this is rarely necessary, unless you are
dealing with a situation which is known to confuse Perl's
method caching.
Returns an integer which is incremented every time a local
method of or the @ISA of the given package changes on
Perl 5.9.5+. On earlier Perls with this the MRO::Compat manpage module,
it will probably increment a lot more often than necessary.
While this module makes the 5.9.5+ syntaxes
use mro 'c3' and mro::set_mro("Foo", 'c3') available
on older Perls, it does so merely by passing off the work
to the Class::C3 manpage.
It does not remove the need for you to call
Class::C3::initialize(), Class::C3::reinitialize(), and/or
Class::C3::uninitialize() at the appropriate times
as documented in the the Class::C3 manpage docs. These three functions
are always provided by the MRO::Compat manpage, either via the Class::C3 manpage
itself on older Perls, or directly as no-ops on 5.9.5+.
the Class::C3 manpage
mro
Brandon L. Black, <blblack@gmail.com>
Copyright 2007-2008 Brandon L. Black <blblack@gmail.com>
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
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