First, let's assume the following directory structure and class files, and that the top level directory and library directory are on the include_path:
application/
modules/
foo/
views/
helpers/
FormLabel.php
FormSubmit.php
bar/
views/
helpers/
FormSubmit.php
library/
Zend/
View/
Helper/
FormLabel.php
FormSubmit.php
FormText.php
Now, let's create a plugin loader to address the various view helper repositories available:
<?php
$loader = new Zend_Loader_PluginLoader();
$loader->addPrefixPath('Zend_View_Helper', 'Zend/View/Helper/')
->addPrefixPath('Foo_View_Helper',
'application/modules/foo/views/helpers')
->addPrefixPath('Bar_View_Helper',
'application/modules/bar/views/helpers');
We can then load a given view helper using just the portion of the class name following the prefixes as defined when adding the paths:
<?php
// load 'FormText' helper:
$formTextClass = $loader->load('FormText'); // 'Zend_View_Helper_FormText';
// load 'FormLabel' helper:
$formLabelClass = $loader->load('FormLabel'); // 'Foo_View_Helper_FormLabel'
// load 'FormSubmit' helper:
$formSubmitClass = $loader->load('FormSubmit'); // 'Bar_View_Helper_FormSubmit'
Once the class is loaded, we can now instantiate it.
Note
In some cases, you may use the same prefix for multiple paths.
Zend_Loader_PluginLoader actually registers an
array of paths for each given prefix; the last one registered
will be the first one checked. This is particularly useful if
you are utilizing incubator components.
Paths may be defined at instantiation
You may optionally provide an array of prefix / path pairs (or prefix / paths -- plural paths are allowed) as a parameter to the constructor:
<?php
$loader = new Zend_Loader_PluginLoader(array(
'Zend_View_Helper' => 'Zend/View/Helper/',
'Foo_View_Helper' => 'application/modules/foo/views/helpers',
'Bar_View_Helper' => 'application/modules/bar/views/helpers'
));
Zend_Loader_PluginLoader also optionally allows you to
share plugins across plugin-aware objects, without needing to
utilize a singleton instance. It does so via a static registry.
Indicate the registry name at instantiation as the second parameter
to the constructor:
<?php
// Store plugins in static registry 'foobar':
$loader = new Zend_Loader_PluginLoader(array(), 'foobar');
Other components that instantiate the PluginLoader
using the same registry name will then have access to already loaded
paths and plugins.