1 # This module is part of DA, Don Armstrong's Modules, and is released
2 # under the terms of the GPL version 2, or any later version. See the
3 # file README and COPYING for more information. Copyright 2003 by Don
4 # Armstrong <don@donarmstrong.com>.
5 # $Id: Modular.pm,v 1.5 2003/10/25 02:15:04 don Exp $
7 package Class::Modular;
11 Class::Modular -- Modular class generation superclass
17 @ISA = qw(Class::Modular);
22 Class::Modular is a superclass for generating modular classes, where
23 methods can be added into the class from the perspective of the
24 object, rather than the perspective of the class.
26 That is, you can create a class which has a set of generic common
27 functions. Less generic functions can be included or overridden
28 without modifying the base classes. This allows for code to be more
29 modular, and reduces code duplication.
35 new is responsible for blessing and creating a new database superclass.
39 load is responsible for loading database plugins
49 use vars qw($VERSION $DEBUG);
53 use Data::Copy qw(deep_copy); # Used for deep copying objects
56 ($VERSION) = q$Revision: 1.5 $ =~ /\$Revision:\s+([^\s+])/;
57 $DEBUG = 0 unless defined $DEBUG;
65 Usage : $obj = Foo::Bar->new();
66 Function: Creates a new Foo::Bar object
67 Returns : A new Foo::Bar object
70 Aditional arguments can be passed to this creator, and they are
71 stored in $self->{_creation_args}. You can also override the new
72 method in your subclass. It's just provided here for completeness.
77 my ($class,@args) = @_;
79 # We shouldn't be called $me->new, but just in case
80 $class = ref($class) || $class;
85 $self->{_creation_args} = [@args];
94 Usage : $db->load('FOO::Subclass');
95 Function: loads a Class::Modular subclass
97 Args : SCALAR subclass SCALAR options
99 Loads the named subclass into this object if the named subclass has
102 The options scalar is passed to $subclass::_methods when determining
103 which methods should be added using _addmethods.
105 The subclasses _init method is called right after methods are loaded.
107 If debugging is enabled, will warn about loading already loaded
114 my ($self,$subclass,$options) = @_;
118 # check to see if the subclass has already been loaded.
120 if (not defined $self->{_subclasses}->{$subclass}){
123 $self->_addmethods($subclass,&{"${subclass}::_methods"}($self,$options));
124 &{"${subclass}::_init"}($self);
127 $self->{_subclasses}->{$subclass} = {};
130 carp "Not reloading subclass $subclass" if $DEBUG;
137 Usage : $self->_addmethods()
138 Function: Adds the passed methods into the function table
140 Args : ARRAY of methods
142 Given an array of methods, adds the methods into the _methodhash
145 Methods that have previously been overridden by override are _NOT_
146 overridden again. This may need to be adjusted in load.
150 sub _addmethods($@) {
151 my ($self,$subclass,@methods) = @_;
153 # stick the method into the table
154 # DLA: Make with the munchies!
156 foreach my $method (@methods) {
157 if (not $method =~ /^$subclass/) {
158 $method = $subclass.$method;
160 my ($method_name) = $method =~ /\:*([^\:]+)\s*$/;
161 if (exists $self->{_methodhash}->{$method_name}) {
162 if ($self->{_methodhash}->{$method_name}->{overridden}) {
163 carp "Not overriding already overriden method $method_name\n" if $DEBUG;
166 carp "Overriding $method_name $self->{_methodhash}->{$method_name}->{reference} with $method\n";
168 $self->{_methodhash}->{$method_name}->{reference} = $method;
176 Usage : $obj->override('methodname', $code_ref)
177 Function: Overrides the method methodname and calls $code_ref instead.
178 Returns : TRUE on success, FALSE on failure.
179 Args : SCALAR method name
180 CODEREF function reference
182 Allows you to override utility functions that are called internally
183 to provide a different default function.
185 It's superficially similar to _addmethods, which is called by load,
186 but it deals with code references, and requires the method name to be
189 Methods overridden here are _NOT_ overrideable in _addmethods. This
190 may need to be changed.
195 my ($self, $method_name, $function_reference) = @_;
197 $self->{_methodhash}->{$method_name}->{reference} = $function_reference;
198 $self->{_methodhash}->{$method_name}->{overridden} = 1;
204 Usage : my $clone = $obj->clone
205 Function: Produces a clone of the Class::Modular object
209 Produces a clone of the object with duplicates of all data and/or new
210 connections as appropriate.
212 Calls _clone on all loaded subclasses.
214 Warns if debugging is on for classes which don't have a _clone
215 method. Dies on other errors.
223 bless $clone, ref($self);
225 # copy data structures at this level
226 $clone->{_methodhash} = deep_copy($self->{_methodhash});
227 $clone->{_subclasses} = deep_copy($self->{_subclasses});
229 foreach my $subclass (keys %{$self->{_subclasses}}) {
230 # use eval to try and call the subclasses _clone method.
231 # Ignore no such function errors, but trap other types of
234 # XXX Switch to can instead.
237 &$subclass::_clone($self,$clone);
240 # Die unless we've hit an undefined subroutine.
241 die $@ unless $@ =~ /Undefined\s*subroutine\s*\&.*\:\:\_clone/;
242 warn "$subclass doesn't have a _clone method\n$@" if $DEBUG;
254 Class::Modular->can('METHOD');
258 Replaces UNIVERSAL's can method so that handled methods are reported
259 correctly. Calls UNIVERSAL::can in the places where
263 A coderef to the method if the method is supported, undef otherwise.
272 my ($self,$method,$vars) = @_;
274 if (ref $self and exists $self->{_methodhash}->{$method}) {
275 # If the method is defined, return a reference to the
277 return $self->{_methodhash}->{$method}->{reference};
280 # Otherwise, let UNIVERSAL::can deal with the method
282 return UNIVERSAL::can($self,$method);
295 Calls all subclass _destroy methods.
297 Subclasses need only implement a _destroy method if they have
298 references that need to be uncircularized, or things that should be
299 disconnected or closed.
305 foreach my $subclass (keys %{$self->{_subclasses}}) {
306 # use eval to try and call the subclasses _destroy method.
307 # Ignore no such function errors, but trap other types of
311 &$subclass::_destroy($self);
314 # Die unless we've hit an undefined subroutine.
315 die $@ unless $@ =~ /Undefined\s*subroutine\s*\&.*\:\:\_clone/;
316 warn "$subclass doesn't have a _clone method\n$@" if $DEBUG;
325 Usage : Called by perl
326 Function: Calls child methods which have been installed into this handle
330 The AUTOLOAD function is responsible for calling child methods which
331 have been installed into the current Class::Modular handle.
333 Subclasses that have a new function as well as an AUTOLOAD function
334 must call Class::Modular::AUTOLOAD and set $Class::Modular::AUTOLOAD
336 $Class::Modular::AUTOLOAD = $AUTOLOAD;
337 goto &Class::Modular::AUTOLOAD;
342 my $method = $AUTOLOAD;
348 if (not ref($self)) {
349 carp "Not a reference in AUTOLOAD.";
353 if (defined $self->{_methodhash}->{$method}->{reference}) {
356 goto &$self->{_methodhash}->{$method}->{reference};