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129 | .\" ======================================================================== |
130 | .\" |
131 | .IX Title "Data::Visitor::Callback 3" |
132 | .TH Data::Visitor::Callback 3 "2009-08-14" "perl v5.8.7" "User Contributed Perl Documentation" |
133 | .SH "NAME" |
134 | Data::Visitor::Callback \- A Data::Visitor with callbacks. |
135 | .SH "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
137 | .Vb 1 |
138 | \& use Data::Visitor::Callback; |
139 | .Ve |
140 | .PP |
141 | .Vb 5 |
142 | \& my $v = Data::Visitor::Callback\->new( |
143 | \& value => sub { ... }, |
144 | \& array => sub { ... }, |
145 | \& object => "visit_ref", # can also use method names |
146 | \& ); |
147 | .Ve |
148 | .PP |
149 | .Vb 1 |
150 | \& $v\->visit( $some_perl_value ); |
151 | .Ve |
152 | .SH "DESCRIPTION" |
153 | .IX Header "DESCRIPTION" |
154 | This is a Data::Visitor subclass that lets you invoke callbacks instead of |
155 | needing to subclass yourself. |
156 | .SH "METHODS" |
157 | .IX Header "METHODS" |
158 | .ie n .IP "new %opts\fR, \f(CW%callbacks" 4 |
159 | .el .IP "new \f(CW%opts\fR, \f(CW%callbacks\fR" 4 |
160 | .IX Item "new %opts, %callbacks" |
161 | Construct a new visitor. |
162 | .Sp |
163 | The options supported are: |
164 | .RS 4 |
165 | .IP "ignore_return_values" 4 |
166 | .IX Item "ignore_return_values" |
167 | When this is true (off by default) the return values from the callbacks are |
168 | ignored, thus disabling the fmapping behavior as documented in |
169 | Data::Visitor. |
170 | .Sp |
171 | This is useful when you want to modify \f(CW$_\fR directly |
172 | .IP "tied_as_objects" 4 |
173 | .IX Item "tied_as_objects" |
174 | Whether ot not to visit the \*(L"tied\*(R" in perlfunc of a tied structure instead of |
175 | pretending the structure is just a normal one. |
176 | .Sp |
177 | See \*(L"visit_tied\*(R" in Data::Visitor. |
178 | .RE |
179 | .RS 4 |
180 | .RE |
181 | .SH "CALLBACKS" |
182 | .IX Header "CALLBACKS" |
183 | Use these keys for the corresponding callbacks. |
184 | .PP |
185 | The callback is in the form: |
186 | .PP |
187 | .Vb 2 |
188 | \& sub { |
189 | \& my ( $visitor, $data ) = @_; |
190 | .Ve |
191 | .PP |
192 | .Vb 1 |
193 | \& # or you can use $_, it's aliased |
194 | .Ve |
195 | .PP |
196 | .Vb 2 |
197 | \& return $data; # or modified data |
198 | \& } |
199 | .Ve |
200 | .PP |
201 | Within the callback \f(CW$_\fR is aliased to the data, and this is also passed in the |
202 | parameter list. |
203 | .PP |
204 | Any method can also be used as a callback: |
205 | .PP |
206 | .Vb 1 |
207 | \& object => "visit_ref", # visit objects anyway |
208 | .Ve |
209 | .IP "visit" 4 |
210 | .IX Item "visit" |
211 | Called for all values |
212 | .IP "value" 4 |
213 | .IX Item "value" |
214 | Called for non objects, non container (hash, array, glob or scalar ref) values. |
215 | .IP "ref_value" 4 |
216 | .IX Item "ref_value" |
217 | Called after \f(CW\*(C`value\*(C'\fR, for references to regexes, globs and code. |
218 | .IP "plain_value" 4 |
219 | .IX Item "plain_value" |
220 | Called after \f(CW\*(C`value\*(C'\fR for non references. |
221 | .IP "object" 4 |
222 | .IX Item "object" |
223 | Called for blessed objects. |
224 | .Sp |
225 | Since \*(L"visit_object\*(R" in Data::Visitor will not recurse downwards unless you |
226 | delegate to \f(CW\*(C`visit_ref\*(C'\fR, you can specify \f(CW\*(C`visit_ref\*(C'\fR as the callback for |
227 | \&\f(CW\*(C`object\*(C'\fR in order to enter objects. |
228 | .Sp |
229 | It is reccomended that you specify the classes (or base classes) you want |
230 | though, instead of just visiting any object forcefully. |
231 | .IP "Some::Class" 4 |
232 | .IX Item "Some::Class" |
233 | You can use any class name as a callback. This is colled only after the |
234 | \&\f(CW\*(C`object\*(C'\fR callback. |
235 | .Sp |
236 | If the object \f(CW\*(C`isa\*(C'\fR the class then the callback will fire. |
237 | .Sp |
238 | These callbacks are called from least derived to most derived by comparing the |
239 | classes' \f(CW\*(C`isa\*(C'\fR at construction time. |
240 | .IP "object_no_class" 4 |
241 | .IX Item "object_no_class" |
242 | Called for every object that did not have a class callback. |
243 | .IP "object_final" 4 |
244 | .IX Item "object_final" |
245 | The last callback called for objects, useful if you want to post process the |
246 | output of any class callbacks. |
247 | .IP "array" 4 |
248 | .IX Item "array" |
249 | Called for array references. |
250 | .IP "hash" 4 |
251 | .IX Item "hash" |
252 | Called for hash references. |
253 | .IP "glob" 4 |
254 | .IX Item "glob" |
255 | Called for glob references. |
256 | .IP "scalar" 4 |
257 | .IX Item "scalar" |
258 | Called for scalar references. |
259 | .IP "tied" 4 |
260 | .IX Item "tied" |
261 | Called on the return value of \f(CW\*(C`tied\*(C'\fR for all tied containers. Also passes in |
262 | the variable as the second argument. |
263 | .IP "seen" 4 |
264 | .IX Item "seen" |
265 | Called for a reference value encountered a second time. |
266 | .Sp |
267 | Passes in the result mapping as the second argument. |
268 | .SH "AUTHOR" |
269 | .IX Header "AUTHOR" |
270 | Yuval Kogman <nothingmuch@woobling.org> |
271 | .SH "COPYRIGHT & LICENSE" |
272 | .IX Header "COPYRIGHT & LICENSE" |
273 | .Vb 3 |
274 | \& Copyright (c) 2006 Yuval Kogman. All rights reserved |
275 | \& This program is free software; you can redistribute |
276 | \& it and/or modify it under the same terms as Perl itself. |
277 | .Ve |