1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
|
package Class::Adapter::Clear;
# ABSTRACT: A handy base Adapter class that makes no changes
#pod =pod
#pod
#pod =head1 SYNOPSIS
#pod
#pod B<Hello World with CGI.pm the normal way>
#pod
#pod # Load and create the CGI
#pod use CGI;
#pod $q = new CGI;
#pod
#pod # Create the page
#pod print $q->header, # HTTP Header
#pod $q->start_html('hello world'), # Start the page
#pod $q->h1('hello world'), # Hello World!
#pod $q->end_html; # End the page
#pod
#pod B<Hello World with CGI.pm the Adapter'ed way>
#pod
#pod # Load and create the CGI
#pod use CGI;
#pod $q = new CGI;
#pod
#pod # Convert to an Adapter
#pod use Class::Adapter::Clear;
#pod $q = new Class::Adapter::Clear( $q );
#pod
#pod # Create the page
#pod print $q->header, # HTTP Header
#pod $q->start_html('hello world'), # Start the page
#pod $q->h1('hello world'), # Hello World!
#pod $q->end_html; # End the page
#pod
#pod B<Creating a CGI Adapter class using Class::Adapter::Clear>
#pod
#pod package My::CGI;
#pod
#pod use base 'Class::Adapter::Clear';
#pod
#pod # Optional - Create the thing we are decorating auto-magically
#pod sub new {
#pod my $class = shift;
#pod
#pod # Create the object we are decorating
#pod my $query = CGI->new(@_);
#pod
#pod # Wrap it in the Adapter
#pod $class->SUPER::new($query);
#pod }
#pod
#pod # Decorate the h1 method to change what is created
#pod sub h1 {
#pod my $self = shift;
#pod my $str = shift;
#pod
#pod # Do something before the real method call
#pod if ( defined $str and $str eq 'hello world' ) {
#pod $str = 'Hello World!';
#pod }
#pod
#pod $self->_OBJECT_->($str, @_);
#pod }
#pod
#pod =head1 DESCRIPTION
#pod
#pod C<Class::Adapter::Clear> provides the base class for creating one common
#pod type of L<Class::Adapter> classes. For more power, move up to
#pod L<Class::Adapter::Builder>.
#pod
#pod On it's own C<Class::Adapter::Clear> passes all methods through to the same
#pod method in the parent object with the same parameters, responds to
#pod C<-E<gt>isa> like the parent object, and responds to C<-E<gt>can> like
#pod the parent object.
#pod
#pod It looks like a C<Duck>, and it quacks like a C<Duck>.
#pod
#pod On this base, you simple implement whatever method you want to do
#pod something special to.
#pod
#pod # Different method, same parameters
#pod sub method1 {
#pod my $self = shift;
#pod $self->_OBJECT_->method2(@_); # Call a different method
#pod }
#pod
#pod # Same method, different parameters
#pod sub method1 {
#pod my $self = shift;
#pod $self->_OBJECT_->method1( lc($_[0]) ); # Lowercase the param
#pod }
#pod
#pod # Same method, same parameters, tweak the result
#pod sub method1 {
#pod my $self = shift;
#pod my $rv = $self->_OBJECT_->method1(@_);
#pod $rv =~ s/\n/<br>\n/g; # Add line-break HTML tags at each newline
#pod return $rv;
#pod }
#pod
#pod As you can see, the advantage of this full-scale I<Adapter> approach,
#pod compared to inheritance, or function wrapping (see L<Class::Hook>), is
#pod that you have complete and utter freedom to do anything you might need
#pod to do, without stressing the Perl inheritance model or doing anything
#pod unusual or tricky with C<CODE> references.
#pod
#pod You may never need this much power. But when you need it, you B<really>
#pod need it.
#pod
#pod As an aside, Class::Adapter::Clear is implemented with the following
#pod L<Class::Adapter::Builder> formula.
#pod
#pod use Class::Adapter::Builder
#pod ISA => '_OBJECT_',
#pod AUTOLOAD => 1;
#pod
#pod =head1 METHODS
#pod
#pod =head2 new $object
#pod
#pod As does the base L<Class::Adapter> class, the default C<new> constructor
#pod takes a single object as argument and creates a new object which holds the
#pod passed object.
#pod
#pod Returns a new C<Class::Adapter::Clear> object, or C<undef> if you do not pass
#pod in an object.
#pod
#pod =cut
use 5.005;
use strict;
use Class::Adapter::Builder
ISA => '_OBJECT_',
AUTOLOAD => 1;
our $VERSION = '1.09';
1;
__END__
=pod
=encoding UTF-8
=head1 NAME
Class::Adapter::Clear - A handy base Adapter class that makes no changes
=head1 VERSION
version 1.09
=head1 SYNOPSIS
B<Hello World with CGI.pm the normal way>
# Load and create the CGI
use CGI;
$q = new CGI;
# Create the page
print $q->header, # HTTP Header
$q->start_html('hello world'), # Start the page
$q->h1('hello world'), # Hello World!
$q->end_html; # End the page
B<Hello World with CGI.pm the Adapter'ed way>
# Load and create the CGI
use CGI;
$q = new CGI;
# Convert to an Adapter
use Class::Adapter::Clear;
$q = new Class::Adapter::Clear( $q );
# Create the page
print $q->header, # HTTP Header
$q->start_html('hello world'), # Start the page
$q->h1('hello world'), # Hello World!
$q->end_html; # End the page
B<Creating a CGI Adapter class using Class::Adapter::Clear>
package My::CGI;
use base 'Class::Adapter::Clear';
# Optional - Create the thing we are decorating auto-magically
sub new {
my $class = shift;
# Create the object we are decorating
my $query = CGI->new(@_);
# Wrap it in the Adapter
$class->SUPER::new($query);
}
# Decorate the h1 method to change what is created
sub h1 {
my $self = shift;
my $str = shift;
# Do something before the real method call
if ( defined $str and $str eq 'hello world' ) {
$str = 'Hello World!';
}
$self->_OBJECT_->($str, @_);
}
=head1 DESCRIPTION
C<Class::Adapter::Clear> provides the base class for creating one common
type of L<Class::Adapter> classes. For more power, move up to
L<Class::Adapter::Builder>.
On it's own C<Class::Adapter::Clear> passes all methods through to the same
method in the parent object with the same parameters, responds to
C<-E<gt>isa> like the parent object, and responds to C<-E<gt>can> like
the parent object.
It looks like a C<Duck>, and it quacks like a C<Duck>.
On this base, you simple implement whatever method you want to do
something special to.
# Different method, same parameters
sub method1 {
my $self = shift;
$self->_OBJECT_->method2(@_); # Call a different method
}
# Same method, different parameters
sub method1 {
my $self = shift;
$self->_OBJECT_->method1( lc($_[0]) ); # Lowercase the param
}
# Same method, same parameters, tweak the result
sub method1 {
my $self = shift;
my $rv = $self->_OBJECT_->method1(@_);
$rv =~ s/\n/<br>\n/g; # Add line-break HTML tags at each newline
return $rv;
}
As you can see, the advantage of this full-scale I<Adapter> approach,
compared to inheritance, or function wrapping (see L<Class::Hook>), is
that you have complete and utter freedom to do anything you might need
to do, without stressing the Perl inheritance model or doing anything
unusual or tricky with C<CODE> references.
You may never need this much power. But when you need it, you B<really>
need it.
As an aside, Class::Adapter::Clear is implemented with the following
L<Class::Adapter::Builder> formula.
use Class::Adapter::Builder
ISA => '_OBJECT_',
AUTOLOAD => 1;
=head1 METHODS
=head2 new $object
As does the base L<Class::Adapter> class, the default C<new> constructor
takes a single object as argument and creates a new object which holds the
passed object.
Returns a new C<Class::Adapter::Clear> object, or C<undef> if you do not pass
in an object.
=head1 SEE ALSO
L<Class::Adapter>, L<Class::Adapter::Builder>
=head1 SUPPORT
Bugs may be submitted through L<the RT bug tracker|https://rt.cpan.org/Public/Dist/Display.html?Name=Class-Adapter>
(or L<bug-Class-Adapter@rt.cpan.org|mailto:bug-Class-Adapter@rt.cpan.org>).
=head1 AUTHOR
Adam Kennedy <adamk@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2005 by Adam Kennedy.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut
|
