====== Prefilters ======


Implementation is not finished yet! But have a look at the source of  
PHPTAL/PreFilter.php:

http://phptal.org/files/PHPTAL-1.2.1b3.tar.gz


There's base abstract class for prefilters. Previously you had to  
implement interface, now you'll have to extend the class. This change  
allows me to add new ways of filtering in the future without any  
breaking changes in the interface.

The class has methods like ''filterDOM($node)'', ''filter($source)'' — you  
just override which ones you want. You can override all of them at  
once if you need, all will be called.

DOM version lets you edit PHPTAL DOM nodes after they've been parsed  
and edit exactly what PHPTAL "sees".


There's also ''filterDOMFragment($node)'' method. I plan to add  
phptal:filter="name_of_the_filter" attribute, which will let you apply  
filters selectively, e.g. (this is not implemented yet)

   <ul phptal:filter="remove_whitespace">
    <li>IE hates newlines in lists</li>
   </ul>

   <script phptal:filter="minify_javascript">
    etc.
   </script>

I've replaced'' PHPTAL->setPreFilter($filter)'' with ''PHPTAL->addPreFilter 
($filter, $name = null)''. Yes, this means you can have any number of  
filters without workarounds (finally! :)


I wonder if there should be separate method for adding named  
prefilters for use with ''phptal:filter'' only? (e.g. you might want to  
make JS minification prefilter available, but you don't want to minify  
entire file). Currently I expect this to be handled within filter,  
i.e. filter would implement ''filterDOMFragment()'' only, and have  
''filterDOM()'' do nothing.


Is that easy to use? Powerful enough? What do you think?

===== Suggested improvements =====

[[http://lists.motion-twin.com/pipermail/phptal/2009-September/001865.html|link]] [[http://lists.motion-twin.com/pipermail/phptal/2009-September/001871.html|prototype]]

The API looks ok to me, just one thing, since it's not a runtime operation
(in the sense that a php file is generated for the template),  I think it'll
be great if it used something along the lines of Zend_Loader_PluginLoader.

Which basically when setup with paths and class prefixes is able to find
"plugins" in several folders. This would allow to have a set of default
filters in PHPTAL distribution but override them and create new ones easily
just by placing the class files in a directory, not needing to register them
manually at runtime, which once the template is compiled, is of no use.

So -- ''phptal:filter="remove_whitespace"'' -- would automatically try to
include and instantiate a class for that filter.

While -- ''%%PHPTAL->addPreFilter("remove_whitespace")%%'' -- would just store the
name for when compiling the template and instantiate the class then.