1Class::Mix(3)         User Contributed Perl Documentation        Class::Mix(3)
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NAME

6       Class::Mix - dynamic class mixing
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SYNOPSIS

9           use Class::Mix qw(mix_class);
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11           $foobar_object = mix_class("Foo", "Bar")->new;
12           $digest_class = mix_class("Foo", "Bar", {prefix=>"Digest::"});
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14           use Class::Mix qw(genpkg);
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16           $package = genpkg;
17           $package = genpkg("Digest::Foo::");
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DESCRIPTION

20       The "mix_class" function provided by this module dynamically generates
21       `anonymous' classes with specified inheritance.
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FUNCTIONS

24       mix_class(ITEMS ...)
25           This function is used to dynamically generate `anonymous' classes
26           by mixing pre-existing classes.  This is useful where an incomplete
27           class requires use of a mixin in order to become instantiable,
28           several suitable mixins are available, and it is desired to make
29           the choice between mixins at runtime.
30
31           Each ITEM in the argument list is either the name of a class to
32           inherit from (a parent class) or a reference to a hash of options.
33           The @ISA list of the mixture class is set to the list of parent
34           class names, in the order supplied.  The options that may be
35           supplied are:
36
37           mro Specifies the desired method resolution order (MRO) of the
38               mixture class.  See mro for details of the valid values and the
39               default determined by Perl.  Typically, this should be set to
40               c3 if mixing into an existing C3-based class hierarchy.
41
42           prefix
43               Specifies where the resulting package will go.  May be "undef"
44               to indicate that the caller doesn't care (which is the default
45               state).  Otherwise it must be either the empty string (to
46               create a top-level package) or a bareword followed by "::" (to
47               create a package under that name).  For example, "Digest::"
48               could be specified to ensure that the resulting package has a
49               name starting with "Digest::", so that "Digest->new" will
50               accept it as the name of a message digest algorithm.
51
52           The function generates a class of the form described by the
53           arguments, and returns its name.  The same class will be returned
54           by repeated invocations with the same parent class list and
55           options.  The returned name may be used to call a constructor or
56           other class methods of the mixed class.
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58           A class name must be returned because there is no such thing as an
59           anonymous class in Perl.  Classes are referenced by name.  The
60           names that are generated by this function are unique and
61           insignificant.  See "genpkg" below for more information.
62
63           If fewer than two classes to inherit from are specified, the
64           function tries to avoid generating a separate class for the
65           mixture.  If only one parent class is specified then that class may
66           be returned, and if no parent classes are specified then
67           "UNIVERSAL" may be returned.  This provides the desired inheritance
68           without creating superfluous classes.  These special cases only
69           apply if the options are compatible with the pre-existing class.
70
71           This function relies on the classes it returns remaining unmodified
72           in order to be returned by future invocations.  If you want to
73           modify your dynamically-generated `anonymous' classes, use "genpkg"
74           (below).
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76       genpkg([PREFIX])
77           This function selects and returns a package name that has not been
78           previously used.  The name returned is an ordinary bareword-form
79           package name, and can be used as the second argument to "bless" and
80           in all other ways that package names are used.  The package is
81           initially empty.
82
83           The package names returned by this function are of a type that
84           should not be used as ordinary fixed module names.  However, it is
85           not possible to entirely prevent a clash.  This function checks
86           that the package name it is about to return has not already been
87           used, and will avoid returning such names, but it cannot guarantee
88           that a later-loaded module will not create a clash.
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90           PREFIX, if present, specifies where the resulting package will go.
91           It must be either the empty string (to create a top-level package)
92           or a bareword followed by "::" (to create a package under that
93           name).  For example, "Digest::" could be specified to ensure that
94           the resulting package has a name starting with "Digest::", so that
95           "Digest->new" will accept it as the name of a message digest
96           algorithm.  If the PREFIX is not supplied, the caller is not
97           expressing any preference.
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SEE ALSO

100       Class::Generate, mro
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AUTHOR

103       Andrew Main (Zefram) <zefram@fysh.org>
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106       Copyright (C) 2004, 2006, 2009, 2010, 2011, 2017 Andrew Main (Zefram)
107       <zefram@fysh.org>
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LICENSE

110       This module is free software; you can redistribute it and/or modify it
111       under the same terms as Perl itself.
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115perl v5.32.1                      2021-01-27                     Class::Mix(3)
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