Filter hook
The _filter hook was changed significantly. It's best to start with the following framework:
<?php
function hook_filter($op, $delta = 0, $format = -1, $text = '') {
switch ($op) {
case 'list':
return array(0 => t('Filter name'));
case 'description':
return t("Short description of the filter's actions.");
/*
case 'no cache':
return true;
*/
case 'prepare':
$text = ...
return $text;
case 'process':
$text = ...
return $text;
case 'settings':
$output = ...;
return $output;
default:
return $text;
}
}
?>When converting a module to 4.5, you can normally ignore the $delta paramter: it is used to have multiple filters inside one module. The 'prepare', 'process' and 'settings' operations still work the same as before, with only small changes.
However, you should now include the $format parameter in the variable names for filter settings. If your filter has a setting "myfilter_something", it should be changed to "myfilter_something_$format". This allows the setting to be set separately for each input format. To check if it works correctly, add your filter to two different input formats and give each instance different settings. Verify that each input format retains its own settings.
Unlike before, the 'settings' operation should only be used to return actually useful settings, because there is now a separate overview of all enabled filters. A filter does not need its own on/off toggle. If a filter has no configurable settings, it should return nothing for the settings, rather than a message like we did before.
Finally, the filter system now includes caching. If your filter's output is dynamic and should not be cached, uncomment the 'no cache' snippet. Only do this when absolutely necessary, because this turns off caching for any input format your filter is used in. Beware of the filter cache when developing your module: it is advised to uncomment 'no cache' while developing, but be sure to remove it again if it's not needed.