Zend_Filter supplies a set of commonly needed filters, but developers will often need to write custom
filters for their particular use cases. The task of writing a custom filter is facilitated by
implementing Zend_Filter_Interface.
Zend_Filter_Interface defines a single method, filter(), that may be
implemented by user classes. An object that implements this interface may be added to a filter chain
with Zend_Filter::addFilter().
The following example demonstrates how to write a custom filter:
<?php
require_once 'Zend/Filter/Interface.php';
class MyFilter implements Zend_Filter_Interface
{
public function filter($value)
{
// perform some transformation upon $value to arrive on $valueFiltered
return $valueFiltered;
}
}
To add an instance of the above filter to a filter chain:
<?php $filterChain = new Zend_Filter(); $filterChain->addFilter(new MyFilter());