1MRO::Compat(3)        User Contributed Perl Documentation       MRO::Compat(3)
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NAME

6       MRO::Compat - mro::* interface compatibility for Perls < 5.9.5
7

SYNOPSIS

9          package PPP;      use base qw/Exporter/;
10          package X;        use base qw/PPP/;
11          package Y;        use base qw/PPP/;
12          package Z;        use base qw/PPP/;
13
14          package FooClass; use base qw/X Y Z/;
15
16          package main;
17          use MRO::Compat;
18          my $linear = mro::get_linear_isa('FooClass');
19          print join(q{, }, @$linear);
20
21          # Prints: FooClass, X, PPP, Exporter, Y, Z
22

DESCRIPTION

24       The "mro" namespace provides several utilities for dealing with method
25       resolution order and method caching in general in Perl 5.9.5 and
26       higher.
27
28       This module provides those interfaces for earlier versions of Perl
29       (back to 5.6.0 anyways).
30
31       It is a harmless no-op to use this module on 5.9.5+.  That is to say,
32       code which properly uses MRO::Compat will work unmodified on both older
33       Perls and 5.9.5+.
34
35       If you're writing a piece of software that would like to use the parts
36       of 5.9.5+'s mro:: interfaces that are supported here, and you want
37       compatibility with older Perls, this is the module for you.
38
39       Some parts of this code will work better and/or faster with
40       Class::C3::XS installed (which is an optional prereq of Class::C3,
41       which is in turn a prereq of this package), but it's not a requirement.
42
43       This module never exports any functions.  All calls must be fully
44       qualified with the "mro::" prefix.
45
46       The interface documentation here serves only as a quick reference of
47       what the function basically does, and what differences between
48       MRO::Compat and 5.9.5+ one should look out for.  The main docs in
49       5.9.5's mro are the real interface docs, and contain a lot of other
50       useful information.
51

Functions

53   mro::get_linear_isa($classname[, $type])
54       Returns an arrayref which is the linearized "ISA" of the given class.
55       Uses whichever MRO is currently in effect for that class by default, or
56       the given MRO (either "c3" or "dfs" if specified as $type).
57
58       The linearized ISA of a class is a single ordered list of all of the
59       classes that would be visited in the process of resolving a method on
60       the given class, starting with itself.  It does not include any
61       duplicate entries.
62
63       Note that "UNIVERSAL" (and any members of "UNIVERSAL"'s MRO) are not
64       part of the MRO of a class, even though all classes implicitly inherit
65       methods from "UNIVERSAL" and its parents.
66
67   mro::import
68       This allows the "use mro 'dfs'" and "use mro 'c3'" syntaxes, providing
69       you "use MRO::Compat" first.  Please see the "USING C3" section for
70       additional details.
71
72   mro::set_mro($classname, $type)
73       Sets the mro of $classname to one of the types "dfs" or "c3".  Please
74       see the "USING C3" section for additional details.
75
76   mro::get_mro($classname)
77       Returns the MRO of the given class (either "c3" or "dfs").
78
79       It considers any Class::C3-using class to have C3 MRO even before
80       Class::C3::initialize() is called.
81
82   mro::get_isarev($classname)
83       Returns an arrayref of classes who are subclasses of the given
84       classname.  In other words, classes in whose @ISA hierarchy we appear,
85       no matter how indirectly.
86
87       This is much slower on pre-5.9.5 Perls with MRO::Compat than it is on
88       5.9.5+, as it has to search the entire package namespace.
89
90   mro::is_universal($classname)
91       Returns a boolean status indicating whether or not the given classname
92       is either "UNIVERSAL" itself, or one of "UNIVERSAL"'s parents by @ISA
93       inheritance.
94
95       Any class for which this function returns true is "universal" in the
96       sense that all classes potentially inherit methods from it.
97
98   mro::invalidate_all_method_caches
99       Increments "PL_sub_generation", which invalidates method caching in all
100       packages.
101
102       Please note that this is rarely necessary, unless you are dealing with
103       a situation which is known to confuse Perl's method caching.
104
105   mro::method_changed_in($classname)
106       Invalidates the method cache of any classes dependent on the given
107       class.  In MRO::Compat on pre-5.9.5 Perls, this is an alias for
108       "mro::invalidate_all_method_caches" above, as pre-5.9.5 Perls have no
109       other way to do this.  It will still enforce the requirement that you
110       pass it a classname, for compatibility.
111
112       Please note that this is rarely necessary, unless you are dealing with
113       a situation which is known to confuse Perl's method caching.
114
115   mro::get_pkg_gen($classname)
116       Returns an integer which is incremented every time a local method of or
117       the @ISA of the given package changes on Perl 5.9.5+.  On earlier Perls
118       with this MRO::Compat module, it will probably increment a lot more
119       often than necessary.
120

USING C3

122       While this module makes the 5.9.5+ syntaxes "use mro 'c3'" and
123       "mro::set_mro("Foo", 'c3')" available on older Perls, it does so merely
124       by passing off the work to Class::C3.
125
126       It does not remove the need for you to call "Class::C3::initialize()",
127       "Class::C3::reinitialize()", and/or "Class::C3::uninitialize()" at the
128       appropriate times as documented in the Class::C3 docs.  These three
129       functions are always provided by MRO::Compat, either via Class::C3
130       itself on older Perls, or directly as no-ops on 5.9.5+.
131

SEE ALSO

133       Class::C3
134
135       mro
136

AUTHOR

138       Brandon L. Black, <blblack@gmail.com>
139
141       Copyright 2007-2008 Brandon L. Black <blblack@gmail.com>
142
143       This library is free software; you can redistribute it and/or modify it
144       under the same terms as Perl itself.
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148perl v5.28.0                      2017-03-28                    MRO::Compat(3)
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