Codebase list libclass-inner-perl / d0db50e
[svn-inject] Installing original source of libclass-inner-perl Gregor Herrmann 18 years ago
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0 2001-08-12 Piers Cawley <pdcawley@iterative-software.com>
1
2 * Initial release. Everthing working as documented, I think. Now
3 to find out if I'm right, and if what's documented is enough for
4 people
5
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Inner.pm less more
0 package Class::Inner;
1
2 use vars qw/$VERSION/;
3
4 $VERSION = 0.1;
5
6
7 use strict;
8 use Carp;
9
10 =head1 NAME
11
12 Class::Inner - A perlish implementation of Java like inner classes
13
14 =head1 SYNOPSIS
15
16 use Class::Inner;
17
18 my $object = Class::Inner->new(
19 parent => 'ParentClass',
20 methods => { method => sub { ... } }, },
21 constructor => 'new',
22 args => [@constructor_args],
23 );
24
25 =head1 DESCRIPTION
26
27 Yet another implementation of an anonymous class with per object
28 overrideable methods, but with the added attraction of sort of working
29 dispatch to the parent class's method.
30
31 =head2 METHODS
32
33 =over 4
34
35 =item B<new HASH>
36
37 Takes a hash like argument list with the following keys.
38
39 =over 4
40
41 =item B<parent>
42
43 The name of the parent class. Note that you can only get single
44 inheritance with this or B<SUPER> won't work.
45
46 =item B<methods>
47
48 A hash, keys are method names, values are CODEREFs.
49
50 =item B<constructor>
51
52 The name of the constructor method. Defaults to 'new'.
53
54 =item B<args>
55
56 An anonymous array of arguments to pass to the constructor. Defaults
57 to an empty list.
58
59 =back
60
61 Returns an object in an 'anonymous' class which inherits from the
62 parent class. This anonymous class has a couple of 'extra' methods:
63
64 =over 4
65
66 =item B<SUPER>
67
68 If you were to pass something like
69
70 $obj = Class::Inner->new(
71 parent => 'Parent',
72 methods => { method => sub { ...; $self->SUPER::method(@_) } },
73 );
74
75 then C<$self-C<gt>SUPER::method> almost certainly wouldn't do what you expect,
76 so we provide the C<SUPER> method which dispatches to the parent
77 implementation of the current method. There seems to be no good way of
78 getting the full C<SUPER::> functionality, but I'm working on it.
79
80 =item B<DESTROY>
81
82 Because B<Class::Inner> works by creating a whole new class name for your
83 object, it could potentially leak memory if you create a lot of them. So we
84 add a C<DESTROY> method that removes the class from the symbol table once
85 it's finished with.
86
87 If you need to override a parent's DESTROY method, adding a call to
88 C<Class::Inner::clean_symbol_table(ref $self)> to it. Do it at the
89 end of the method or your other method calls won't work.
90
91 =back
92
93 =cut
94
95 #'
96
97 sub new {
98 my $class = shift;
99 my %args = ref($_[0]) ? %{$_[0]} : @_;
100 my $parent = $args{parent} or
101 croak "Can't work without a parent class\n";
102 my %methods = %{$args{methods}||{}};
103 my $constructor = $args{constructor} || 'new';
104 my @constructor_args = @{$args{args} || []};
105
106 my $anon_class = $class->new_classname;
107
108 no strict 'refs';
109
110 @{"$anon_class\::ISA"} = $parent;
111
112 foreach my $methodname (keys %methods) {
113 *{"$anon_class\::$methodname"} = sub {
114 local $Class::Inner::target_method = $methodname;
115 $methods{$methodname}->(@_);
116 };
117 }
118
119 # Add the SUPER method.
120
121 unless (exists $methods{SUPER}) {
122 *{"$anon_class\::SUPER"} = sub {
123 my $self = shift;
124 my $target_method =
125 join '::', $parent, $Class::Inner::target_method;
126 $self->$target_method(@_);
127 };
128 }
129
130 unless (exists $methods{DESTROY}) {
131 *{"$anon_class\::DESTROY"} = sub {
132 my $self = shift;
133 Class::Inner::clean_symbol_table($anon_class);
134 bless $self, $parent;
135 }
136 }
137 # Instantiate
138 my $obj = $anon_class->new(@constructor_args);
139 }
140
141 =item B<clean_symbol_table>
142
143 The helper subroutine that DESTROY uses to remove the class from the
144 symbol table.
145
146 =cut
147
148 sub clean_symbol_table {
149 my $class = shift;
150 no strict 'refs';
151 foreach my $symbol (keys %{"$class\::"}) {
152 delete ${"$class\::"}{$symbol};
153 }
154 delete $::{"$class\::"};
155 }
156
157 =item B<new_classname>
158
159 Returns a name for the next anonymous class.
160
161 =cut
162
163 {
164 my $class_counter;
165
166 sub new_classname {
167 my $baseclass = ref($_[0]) || $_[0];
168 return "$baseclass\::__A" . $class_counter++;
169 }
170 }
171
172 1;
173 __END__
174
175 =back
176
177 =head1 AUTHOR
178
179 Copyright (c) 2001 by Piers Cawley E<lt>pdcawley@iterative-software.comE<gt>.
180
181 All rights reserved. This program is free software; you can redistribute it
182 and/or modify it under the same terms as perl itself.
183
184 Thanks to the Iterative Software people: Leon Brocard, Natalie Ford and
185 Dave Cross. Also, this module was written initially for use in the
186 PerlUnit project, AKA Test::Unit. Kudos to Christian Lemburg and the rest
187 of that team.
188
189 =head1 SEE ALSO
190
191 There are a million and one differen Class constructors available on CPAN,
192 none of them does quite what I want, so I wrote this one to add to
193 that population where hopefully it will live and thrive.
194
195 =head1 BUGS
196
197 Bound to be some. Actually the C<SUPER> method is a workaround for what
198 I consider to be a bug in perl.
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MANIFEST less more
0 Changes
1 Inner.pm
2 MANIFEST
3 README
4 Makefile.PL
5 t/basic.t
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Makefile.PL less more
0 use ExtUtils::MakeMaker;
1 # See lib/ExtUtils/MakeMaker.pm for details of how to influence
2 # the contents of the Makefile that is written.
3 WriteMakefile(
4 'NAME' => 'Class::Inner',
5 'VERSION_FROM' => 'Inner.pm', # finds $VERSION
6 'PREREQ_PM' => {}, # e.g., Module::Name => 1.1
7 );
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README less more
0 INSTALLATION
1 Just perform the usual incantation:
2
3 gunzip Class-Inner-0.1.tar.gz
4 tar -xvf Class-Inner-0.1.tar
5 cd Class-Inner-0.1
6 perl Makefile.PL
7 make
8 make test
9 make install
10
11 AUTHOR
12 Copyright (c) 2001 Piers Cawley, <pdcawley@iterative-software.com>.
13
14 All rights reserved. This program is free software; you can
15 redistribute it and/or modify it under the same terms as
16 Perl itself.
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t/basic.t less more
0 #!/usr/bin/perl -w
1
2 use strict;
3
4 use Test::More qw/no_plan/;
5
6 BEGIN { use_ok( 'Class::Inner' ); }
7
8 package Parent;
9
10 sub new { my $class = shift; bless [@_], $class }
11 sub a { 'A' };
12 sub b { 'B' };
13 sub poly { $_[0]->b }
14
15 package main;
16
17 ok(my $p = Parent->new, "Parent can instantiate");
18 ok($p->isa('Parent'), '$p is a Parent');
19 is($p->a(), 'A', '$p->a is A');
20 is($p->b(), 'B', '$p->b is B');
21 is($p->poly(), 'B', '$p->poly is B');
22
23 my $ic = Class::Inner->new(
24 parent => 'Parent',
25 methods => { b => sub {
26 my $self = shift;
27 lc($self->SUPER);
28 },
29 c => sub { 'C' } },
30 args => [qw/a b c/]
31 );
32
33 ok(ref($ic) && $ic->isa('Parent'),
34 '$ic is a Parent');
35 my $ic_class = ref($ic); # Remember this for later...
36 ok(eq_array($ic, [qw/a b c/]), 'constructor test');
37
38 is($ic->a(), 'A', '$ic->a is A');
39 is($ic->b(), 'b', '$ic->b is b');
40 is($ic->c(), 'C', '$ic->c is C');
41 is($ic->poly(), 'b', '$ic->poly is b');
42
43 # Check that destruction works.
44
45 $ic = undef;
46
47 ok(!$ic_class->isa('Parent'), 'Class dismissed');