Class::Loader(3) User Contributed Perl Documentation Class::Loader(3)NAMEClass::Loader - Load modules and create objects on demand.
VERSION
$Revision: 2.2 $
$Date: 2001/07/18 20:21:39 $
SYNOPSIS
package Web::Server;
use Class::Loader;
@ISA = qw(Class::Loader);
$self->_load( 'Content_Handler', {
Module => "Filter::URL",
Constructor => "new",
Args => [ ],
}
);
DESCRIPTION
Certain applications like to defer the decision to use a particular
module till runtime. This is possible in perl, and is a useful trick in
situations where the type of data is not known at compile time and the
application doesn't wish to pre-compile modules to handle all types of
data it can work with. Loading modules at runtime can also provide
flexible interfaces for perl modules. Modules can let the programmer
decide what modules will be used by it instead of hard-coding their
names.
Class::Loader is an inheritable class that provides a method, _load(),
to load a module from disk and construct an object by calling its
constructor. It also provides a way to map modules names and associated
metadata with symbolic names that can be used in place of module names
at _load().
METHODSnew()
A basic constructor. You can use this to create an object of
Class::Loader, in case you don't want to inherit Class::Loader.
_load()_load() loads a module and calls its constructor. It returns the
newly constructed object on success or a non-true value on failure.
The first argument can be the name of the key in which the returned
object is stored. This argument is optional. The second (or the
first) argument is a hash which can take the following keys:
Module
This is name of the class to load. (It is not the module's
filename.)
Name
Symbolic name of the module defined with _storemap(). Either
one of Module or Name keys must be present in a call to
_load().
Constructor
Name of the Module constructor. Defaults to "new".
Args
A reference to the list of arguments for the constructor.
_load() calls the constructor with this list. If no Args are
present, _load() will call the constructor without any
arguments.
CPAN
If the Module is not installed on the local system, _load() can
fetch & install it from CPAN provided the CPAN key is present.
This functionality assumes availability of a pre-configured
CPAN shell.
_storemap()Class::Loader maintains a class table that maps symbolic names to
parameters accepted by _load(). It takes a hash as argument whose
keys are symbolic names and value are hash references that contain
a set of _load() arguments. Here's an example:
$self->_storemap ( "URL" => { Module => "Filter::URL",
Constructor => "foo",
Args => [qw(bar baz)],
}
);
# time passes...
$self->{handler} = $self->_load ( Name => 'URL' );
_retrmap()_retrmap() returns the entire map stored with Class::Loader.
Class::Loader maintains separate maps for different classes, and
_retrmap() returns the map valid in the caller class.
SEE ALSOAnyLoader(3)AUTHOR
Vipul Ved Prakash, <mail@vipul.net>
LICENSE
Copyright (c) 2001, Vipul Ved Prakash. All rights reserved. This code
is free software; you can redistribute it and/or modify it under the
same terms as Perl itself.
perl v5.14.0 2011-06-17 Class::Loader(3)