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129 | .\" ======================================================================== |
130 | .\" |
131 | .IX Title "Template::Plugin::Filter 3" |
132 | .TH Template::Plugin::Filter 3 "2009-07-04" "perl v5.8.7" "User Contributed Perl Documentation" |
133 | .SH "NAME" |
134 | Template::Plugin::Filter \- Base class for plugin filters |
135 | .SH "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
137 | .Vb 1 |
138 | \& package MyOrg::Template::Plugin::MyFilter; |
139 | .Ve |
140 | .PP |
141 | .Vb 2 |
142 | \& use Template::Plugin::Filter; |
143 | \& use base qw( Template::Plugin::Filter ); |
144 | .Ve |
145 | .PP |
146 | .Vb 2 |
147 | \& sub filter { |
148 | \& my ($self, $text) = @_; |
149 | .Ve |
150 | .PP |
151 | .Vb 1 |
152 | \& # ...mungify $text... |
153 | .Ve |
154 | .PP |
155 | .Vb 2 |
156 | \& return $text; |
157 | \& } |
158 | .Ve |
159 | .PP |
160 | .Vb 2 |
161 | \& # now load it... |
162 | \& [% USE MyFilter %] |
163 | .Ve |
164 | .PP |
165 | .Vb 4 |
166 | \& # ...and use the returned object as a filter |
167 | \& [% FILTER $MyFilter %] |
168 | \& ... |
169 | \& [% END %] |
170 | .Ve |
171 | .SH "DESCRIPTION" |
172 | .IX Header "DESCRIPTION" |
173 | This module implements a base class for plugin filters. It hides |
174 | the underlying complexity involved in creating and using filters |
175 | that get defined and made available by loading a plugin. |
176 | .PP |
177 | To use the module, simply create your own plugin module that is |
178 | inherited from the \f(CW\*(C`Template::Plugin::Filter\*(C'\fR class. |
179 | .PP |
180 | .Vb 1 |
181 | \& package MyOrg::Template::Plugin::MyFilter; |
182 | .Ve |
183 | .PP |
184 | .Vb 2 |
185 | \& use Template::Plugin::Filter; |
186 | \& use base qw( Template::Plugin::Filter ); |
187 | .Ve |
188 | .PP |
189 | Then simply define your \f(CW\*(C`filter()\*(C'\fR method. When called, you get |
190 | passed a reference to your plugin object (\f(CW$self\fR) and the text |
191 | to be filtered. |
192 | .PP |
193 | .Vb 2 |
194 | \& sub filter { |
195 | \& my ($self, $text) = @_; |
196 | .Ve |
197 | .PP |
198 | .Vb 1 |
199 | \& # ...mungify $text... |
200 | .Ve |
201 | .PP |
202 | .Vb 2 |
203 | \& return $text; |
204 | \& } |
205 | .Ve |
206 | .PP |
207 | To use your custom plugin, you have to make sure that the Template |
208 | Toolkit knows about your plugin namespace. |
209 | .PP |
210 | .Vb 3 |
211 | \& my $tt2 = Template\->new({ |
212 | \& PLUGIN_BASE => 'MyOrg::Template::Plugin', |
213 | \& }); |
214 | .Ve |
215 | .PP |
216 | Or for individual plugins you can do it like this: |
217 | .PP |
218 | .Vb 5 |
219 | \& my $tt2 = Template\->new({ |
220 | \& PLUGINS => { |
221 | \& MyFilter => 'MyOrg::Template::Plugin::MyFilter', |
222 | \& }, |
223 | \& }); |
224 | .Ve |
225 | .PP |
226 | Then you \f(CW\*(C`USE\*(C'\fR your plugin in the normal way. |
227 | .PP |
228 | .Vb 1 |
229 | \& [% USE MyFilter %] |
230 | .Ve |
231 | .PP |
232 | The object returned is stored in the variable of the same name, |
233 | \&'\f(CW\*(C`MyFilter\*(C'\fR'. When you come to use it as a \f(CW\*(C`FILTER\*(C'\fR, you should add |
234 | a dollar prefix. This indicates that you want to use the filter |
235 | stored in the variable '\f(CW\*(C`MyFilter\*(C'\fR' rather than the filter named |
236 | \&'\f(CW\*(C`MyFilter\*(C'\fR', which is an entirely different thing (see later for |
237 | information on defining filters by name). |
238 | .PP |
239 | .Vb 3 |
240 | \& [% FILTER $MyFilter %] |
241 | \& ...text to be filtered... |
242 | \& [% END %] |
243 | .Ve |
244 | .PP |
245 | You can, of course, assign it to a different variable. |
246 | .PP |
247 | .Vb 1 |
248 | \& [% USE blat = MyFilter %] |
249 | .Ve |
250 | .PP |
251 | .Vb 3 |
252 | \& [% FILTER $blat %] |
253 | \& ...text to be filtered... |
254 | \& [% END %] |
255 | .Ve |
256 | .PP |
257 | Any configuration parameters passed to the plugin constructor from the |
258 | \&\f(CW\*(C`USE\*(C'\fR directive are stored internally in the object for inspection by |
259 | the \f(CW\*(C`filter()\*(C'\fR method (or indeed any other method). Positional |
260 | arguments are stored as a reference to a list in the \f(CW\*(C`_ARGS\*(C'\fR item while |
261 | named configuration parameters are stored as a reference to a hash |
262 | array in the \f(CW\*(C`_CONFIG\*(C'\fR item. |
263 | .PP |
264 | For example, loading a plugin as shown here: |
265 | .PP |
266 | .Vb 1 |
267 | \& [% USE blat = MyFilter 'foo' 'bar' baz = 'blam' %] |
268 | .Ve |
269 | .PP |
270 | would allow the \f(CW\*(C`filter()\*(C'\fR method to do something like this: |
271 | .PP |
272 | .Vb 2 |
273 | \& sub filter { |
274 | \& my ($self, $text) = @_; |
275 | .Ve |
276 | .PP |
277 | .Vb 2 |
278 | \& my $args = $self\->{ _ARGS }; # [ 'foo', 'bar' ] |
279 | \& my $conf = $self\->{ _CONFIG }; # { baz => 'blam' } |
280 | .Ve |
281 | .PP |
282 | .Vb 1 |
283 | \& # ...munge $text... |
284 | .Ve |
285 | .PP |
286 | .Vb 2 |
287 | \& return $text; |
288 | \& } |
289 | .Ve |
290 | .PP |
291 | By default, plugins derived from this module will create static |
292 | filters. A static filter is created once when the plugin gets |
293 | loaded via the \f(CW\*(C`USE\*(C'\fR directive and re-used for all subsequent |
294 | \&\f(CW\*(C`FILTER\*(C'\fR operations. That means that any argument specified with |
295 | the \f(CW\*(C`FILTER\*(C'\fR directive are ignored. |
296 | .PP |
297 | Dynamic filters, on the other hand, are re-created each time |
298 | they are used by a \f(CW\*(C`FILTER\*(C'\fR directive. This allows them to act |
299 | on any parameters passed from the \f(CW\*(C`FILTER\*(C'\fR directive and modify |
300 | their behaviour accordingly. |
301 | .PP |
302 | There are two ways to create a dynamic filter. The first is to |
303 | define a \f(CW$DYNAMIC\fR class variable set to a true value. |
304 | .PP |
305 | .Vb 3 |
306 | \& package MyOrg::Template::Plugin::MyFilter; |
307 | \& use base 'Template::Plugin::Filter'; |
308 | \& our $DYNAMIC = 1; |
309 | .Ve |
310 | .PP |
311 | The other way is to set the internal \f(CW\*(C`_DYNAMIC\*(C'\fR value within the \f(CW\*(C`init()\*(C'\fR |
312 | method which gets called by the \f(CW\*(C`new()\*(C'\fR constructor. |
313 | .PP |
314 | .Vb 5 |
315 | \& sub init { |
316 | \& my $self = shift; |
317 | \& $self\->{ _DYNAMIC } = 1; |
318 | \& return $self; |
319 | \& } |
320 | .Ve |
321 | .PP |
322 | When this is set to a true value, the plugin will automatically |
323 | create a dynamic filter. The outcome is that the \f(CW\*(C`filter()\*(C'\fR method |
324 | will now also get passed a reference to an array of postional |
325 | arguments and a reference to a hash array of named parameters. |
326 | .PP |
327 | So, using a plugin filter like this: |
328 | .PP |
329 | .Vb 1 |
330 | \& [% FILTER $blat 'foo' 'bar' baz = 'blam' %] |
331 | .Ve |
332 | .PP |
333 | would allow the \f(CW\*(C`filter()\*(C'\fR method to work like this: |
334 | .PP |
335 | .Vb 2 |
336 | \& sub filter { |
337 | \& my ($self, $text, $args, $conf) = @_; |
338 | .Ve |
339 | .PP |
340 | .Vb 3 |
341 | \& # $args = [ 'foo', 'bar' ] |
342 | \& # $conf = { baz => 'blam' } |
343 | \& } |
344 | .Ve |
345 | .PP |
346 | In this case can pass parameters to both the \s-1USE\s0 and \s-1FILTER\s0 directives, |
347 | so your \fIfilter()\fR method should probably take that into account. |
348 | .PP |
349 | .Vb 1 |
350 | \& [% USE MyFilter 'foo' wiz => 'waz' %] |
351 | .Ve |
352 | .PP |
353 | .Vb 3 |
354 | \& [% FILTER $MyFilter 'bar' biz => 'baz' %] |
355 | \& ... |
356 | \& [% END %] |
357 | .Ve |
358 | .PP |
359 | You can use the \f(CW\*(C`merge_args()\*(C'\fR and \f(CW\*(C`merge_config()\*(C'\fR methods to do a quick |
360 | and easy job of merging the local (e.g. \f(CW\*(C`FILTER\*(C'\fR) parameters with the |
361 | internal (e.g. \f(CW\*(C`USE\*(C'\fR) values and returning new sets of conglomerated |
362 | data. |
363 | .PP |
364 | .Vb 2 |
365 | \& sub filter { |
366 | \& my ($self, $text, $args, $conf) = @_; |
367 | .Ve |
368 | .PP |
369 | .Vb 2 |
370 | \& $args = $self\->merge_args($args); |
371 | \& $conf = $self\->merge_config($conf); |
372 | .Ve |
373 | .PP |
374 | .Vb 4 |
375 | \& # $args = [ 'foo', 'bar' ] |
376 | \& # $conf = { wiz => 'waz', biz => 'baz' } |
377 | \& ... |
378 | \& } |
379 | .Ve |
380 | .PP |
381 | You can also have your plugin install itself as a named filter by |
382 | calling the \f(CW\*(C`install_filter()\*(C'\fR method from the \f(CW\*(C`init()\*(C'\fR method. You |
383 | should provide a name for the filter, something that you might |
384 | like to make a configuration option. |
385 | .PP |
386 | .Vb 6 |
387 | \& sub init { |
388 | \& my $self = shift; |
389 | \& my $name = $self\->{ _CONFIG }\->{ name } || 'myfilter'; |
390 | \& $self\->install_filter($name); |
391 | \& return $self; |
392 | \& } |
393 | .Ve |
394 | .PP |
395 | This allows the plugin filter to be used as follows: |
396 | .PP |
397 | .Vb 1 |
398 | \& [% USE MyFilter %] |
399 | .Ve |
400 | .PP |
401 | .Vb 3 |
402 | \& [% FILTER myfilter %] |
403 | \& ... |
404 | \& [% END %] |
405 | .Ve |
406 | .PP |
407 | or |
408 | .PP |
409 | .Vb 1 |
410 | \& [% USE MyFilter name = 'swipe' %] |
411 | .Ve |
412 | .PP |
413 | .Vb 3 |
414 | \& [% FILTER swipe %] |
415 | \& ... |
416 | \& [% END %] |
417 | .Ve |
418 | .PP |
419 | Alternately, you can allow a filter name to be specified as the |
420 | first positional argument. |
421 | .PP |
422 | .Vb 6 |
423 | \& sub init { |
424 | \& my $self = shift; |
425 | \& my $name = $self\->{ _ARGS }\->[0] || 'myfilter'; |
426 | \& $self\->install_filter($name); |
427 | \& return $self; |
428 | \& } |
429 | .Ve |
430 | .PP |
431 | .Vb 1 |
432 | \& [% USE MyFilter 'swipe' %] |
433 | .Ve |
434 | .PP |
435 | .Vb 3 |
436 | \& [% FILTER swipe %] |
437 | \& ... |
438 | \& [% END %] |
439 | .Ve |
440 | .SH "EXAMPLE" |
441 | .IX Header "EXAMPLE" |
442 | Here's a complete example of a plugin filter module. |
443 | .PP |
444 | .Vb 3 |
445 | \& package My::Template::Plugin::Change; |
446 | \& use Template::Plugin::Filter; |
447 | \& use base qw( Template::Plugin::Filter ); |
448 | .Ve |
449 | .PP |
450 | .Vb 2 |
451 | \& sub init { |
452 | \& my $self = shift; |
453 | .Ve |
454 | .PP |
455 | .Vb 1 |
456 | \& $self\->{ _DYNAMIC } = 1; |
457 | .Ve |
458 | .PP |
459 | .Vb 2 |
460 | \& # first arg can specify filter name |
461 | \& $self\->install_filter($self\->{ _ARGS }\->[0] || 'change'); |
462 | .Ve |
463 | .PP |
464 | .Vb 2 |
465 | \& return $self; |
466 | \& } |
467 | .Ve |
468 | .PP |
469 | .Vb 2 |
470 | \& sub filter { |
471 | \& my ($self, $text, $args, $config) = @_; |
472 | .Ve |
473 | .PP |
474 | .Vb 2 |
475 | \& $config = $self\->merge_config($config); |
476 | \& my $regex = join('|', keys %$config); |
477 | .Ve |
478 | .PP |
479 | .Vb 1 |
480 | \& $text =~ s/($regex)/$config\->{ $1 }/ge; |
481 | .Ve |
482 | .PP |
483 | .Vb 2 |
484 | \& return $text; |
485 | \& } |
486 | .Ve |
487 | .PP |
488 | .Vb 1 |
489 | \& 1; |
490 | .Ve |
491 | .SH "AUTHOR" |
492 | .IX Header "AUTHOR" |
493 | Andy Wardley <abw@wardley.org> <http://wardley.org/> |
494 | .SH "COPYRIGHT" |
495 | .IX Header "COPYRIGHT" |
496 | Copyright (C) 1996\-2007 Andy Wardley. All Rights Reserved. |
497 | .PP |
498 | This module is free software; you can redistribute it and/or |
499 | modify it under the same terms as Perl itself. |
500 | .SH "SEE ALSO" |
501 | .IX Header "SEE ALSO" |
502 | Template::Plugin, Template::Filters, Template::Manual::Filters |