Table of Contents
The Zend_Loader class includes methods to help you load files dynamically.
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Zend_Loader vs. require_once() |
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The |
The static method Zend_Loader::loadFile()
loads a PHP
file. The file loaded may contain any PHP code.
The method is a wrapper for the PHP function
include()
.
This method returns boolean false on failure, for example
if the specified file does not exist.
Example 30.1. Example of the loadFile() Method
Zend_Loader::loadFile($filename, $dirs=null, $once=false);
The $filename
argument specifies the filename to load,
which must not contain any path information.
A security check is performed on $filename
.
The $filename
may only contain alphanumeric characters,
dashes ("-"), underscores ("_"), or periods (".").
No such restriction is placed on the $dirs
argument.
The $dirs
argument specifies which directories to search for
the file in. If the value is NULL
, only the include_path
is searched; if the value is a string or an array, the directory or directories
specified will be searched, followed by the include_path
.
The $once
argument is a boolean. If TRUE
,
Zend_Loader::loadFile()
uses the PHP function
include_once()
for loading the file, otherwise the PHP function
include()
is used.
The static method Zend_Loader::loadClass($class, $dirs)
loads a PHP file and then checks for the existence of the class.
Example 30.2. Example of the loadClass() Method
Zend_Loader::loadClass('Container_Tree', array( '/home/production/mylib', '/home/production/myapp' ) );
The string specifying the class is converted to a relative path by substituting underscores with directory separators for your OS, and appending '.php'. In the example above, 'Container_Tree' becomes 'Container/Tree.php' on Windows.
If $dirs
is a string or an array,
Zend_Loader::loadClass()
searches the directories in
the order supplied. The first matching file is loaded. If the file
does not exist in the specified $dirs
, then the
include_path
for the PHP environment is searched.
If the file is not found or the class does not exist after the load,
Zend_Loader::loadClass()
throws a Zend_Exception
.
Zend_Loader::loadFile()
is used for loading, so the
class name may only contain alphanumeric characters and the hyphen
('-'), underscore ('_'), and period ('.').
The static method Zend_Loader::isReadable($pathname)
returns TRUE
if a file at the specified pathname exists
and is readable, FALSE
otherwise.
Example 30.3. Example of isReadable() method
if (Zend_Loader::isReadable($filename)) { // do something with $filename }
The $filename
argument specifies the filename to
check. This may contain path information.
This method is a wrapper for the PHP function
is_readable()
.
The PHP function does not search the include_path
,
while Zend_Loader::isReadable()
does.
The Zend_Loader
class contains a method you can register with the
PHP SPL autoloader. Zend_Loader::autoload()
is the
callback method. As a convenience, Zend_Loader
provides the
registerAutoload()
function to register its
autoload()
method. If the spl_autoload
extension is not present in your PHP environment, then the
registerAutoload()
method throws a Zend_Exception
.
Example 30.4. Example of registering the autoloader callback method
Zend_Loader::registerAutoload();
After registering the Zend Framework autoload callback, you can
reference classes from Zend Framework without having to load
them explicitly. The autoload()
method uses
Zend_Loader::loadClass()
automatically when you
reference a class.
If you have extended the Zend_Loader
class, you can give an
optional argument to registerAutoload()
, to specify
the class from which to register an autoload()
method.
Example 30.5. Example of registering the autoload callback method from an extended class
Because of the semantics of static function references in PHP,
you must implement code for both loadClass()
and autoload()
, and the autoload()
must call self::loadClass()
. If your
autoload()
method delegates to its parent to
call self::loadClass()
, then it calls the
method of that name in the parent class, not the subclass.
class My_Loader extends Zend_Loader { public static function loadClass($class, $dirs = null) { parent::loadClass($class, $dirs); } public static function autoload($class) { try { self::loadClass($class); return $class; } catch (Exception $e) { return false; } } } Zend_Loader::registerAutoload('My_Loader');
You can remove an autoload callback. The
registerAutoload()
has an optional second argument,
which is TRUE
by default. If this argument is
FALSE
, the autoload callback is unregistered from the
SPL autoload stack.