Class::Mix(3) User Contributed Perl Documentation Class::Mix(3)NAMEClass::Mix - dynamic class mixing
SYNOPSIS
use Class::Mixqw(mix_class);
$foobar_object = mix_class("Foo", "Bar")->new;
$digest_class = mix_class("Foo", "Bar", {prefix=>"Digest::"});
use Class::Mixqw(genpkg);
$package = genpkg;
$package = genpkg("Digest::Foo::");
DESCRIPTION
The "mix_class" function provided by this module dynamically generates
`anonymous' classes with specified inheritance.
FUNCTIONS
mix_class(ITEMS ...)
This function is used to dynamically generate `anonymous' classes
by mixing pre-existing classes. This is useful where an incomplete
class requires use of a mixin in order to become instantiable,
several suitable mixins are available, and it is desired to make
the choice between mixins at runtime.
Each ITEM in the argument list is either the name of a class to
inherit from (a parent class) or a reference to a hash of options.
The @ISA list of the mixture class is set to the list of parent
class names, in the order supplied. The options that may be
supplied are:
mro Specifies the desired method resolution order (MRO) of the
mixture class. See mro for details of the valid values and the
default determined by Perl. Typically, this should be set to
c3 if mixing into an existing C3-based class hierarchy.
prefix
Specifies where the resulting package will go. May be "undef"
to indicate that the caller doesn't care (which is the default
state). Otherwise it must be either the empty string (to
create a top-level package) or a bareword followed by "::" (to
create a package under that name). For example, "Digest::"
could be specified to ensure that the resulting package has a
name starting with "Digest::", so that "Digest->new" will
accept it as the name of a message digest algorithm.
The function generates a class of the form described by the
arguments, and returns its name. The same class will be returned
by repeated invocations with the same parent class list and
options. The returned name may be used to call a constructor or
other class methods of the mixed class.
A class name must be returned because there is no such thing as an
anonymous class in Perl. Classes are referenced by name. The
names that are generated by this function are unique and
insignificant. See "genpkg" below for more information.
If fewer than two classes to inherit from are specified, the
function tries to avoid generating a separate class for the
mixture. If only one parent class is specified then that class may
be returned, and if no parent classes are specified then
"UNIVERSAL" may be returned. This provides the desired inheritance
without creating superfluous classes. These special cases only
apply if the options are compatible with the pre-existing class.
This function relies on the classes it returns remaining unmodified
in order to be returned by future invocations. If you want to
modify your dynamically-generated `anonymous' classes, use "genpkg"
(below).
genpkg([PREFIX])
This function selects and returns a package name that has not been
previously used. The name returned is an ordinary bareword-form
package name, and can be used as the second argument to "bless" and
in all other ways that package names are used. The package is
initially empty.
The package names returned by this function are of a type that
should not be used as ordinary fixed module names. However, it is
not possible to entirely prevent a clash. This function checks
that the package name it is about to return has not already been
used, and will avoid returning such names, but it cannot guarantee
that a later-loaded module will not create a clash.
PREFIX, if present, specifies where the resulting package will go.
It must be either the empty string (to create a top-level package)
or a bareword followed by "::" (to create a package under that
name). For example, "Digest::" could be specified to ensure that
the resulting package has a name starting with "Digest::", so that
"Digest->new" will accept it as the name of a message digest
algorithm. If the PREFIX is not supplied, the caller is not
expressing any preference.
SEE ALSO
Class::Generate, mro
AUTHOR
Andrew Main (Zefram) <zefram@fysh.org>
COPYRIGHT
Copyright (C) 2004, 2006, 2009, 2010, 2011 Andrew Main (Zefram)
<zefram@fysh.org>
LICENSE
This module is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.18.2 2014-05-13 Class::Mix(3)