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Using the Registry - Zend_Registry
A registry is a container for storing objects and values in the application space. By storing the value in a registry, the same object is always available throughout your application. This mechanism is an alternative to using global storage.
The typical method to use registries with Zend Framework is through static methods in the Zend_Registry class. Alternatively, the registry can be used as an array object, so you can access elements stored within it with a convenient array-like interface.
Use the static method set() to store an entry in the registry.
Example #1 Example of set() Method Usage
The value returned can be an object, an array, or a scalar. You can change the value stored in a specific entry of the registry by calling the set() method to set the entry to a new value.
The index can be a scalar (NULL, string, or number), like an ordinary array.
To retrieve an entry from the registry, use the static get() method.
Example #2 Example of get() Method Usage
The getInstance() method returns the singleton registry object. This registry object is iterable, making all values stored in the registry easily accessible.
In addition to accessing the static registry via static methods, you can create an instance directly and use it as an object.
The registry instance you access through the static methods is simply one such instance. It is for convenience that it is stored statically, so that it is accessible from anywhere in an application.
Use the traditional new operator to instantiate Zend_Registry. Instantiating Zend_Registry using its constructor also makes initializing the entries in the registry simple by taking an associative array as an argument.
Example #4 Example of Constructing a Registry
Once such a Zend_Registry object is instantiated, you can use it by calling any array object method or by setting it as the singleton instance for Zend_Registry with the static method setInstance().
Example #5 Example of Initializing the Singleton Registry
The setInstance() method throws a Zend_Exception if the static registry has already been initialized.
If you have several values to get or set, you may find it convenient to access the registry with array notation.
Example #6 Example of Array Access
You may also find it convenient to access the registry in an object-oriented fashion by using index names as object properties. You must specifically construct the registry object using the ArrayObject::ARRAY_AS_PROPS option and initialize the static instance to enable this functionality.
Note: You must set the ArrayObject::ARRAY_AS_PROPS option before the static registry has been accessed for the first time.
Some versions of PHP have proven very buggy when using the registry with the ArrayObject::ARRAY_AS_PROPS option.
Example #7 Example of Object Access
To find out if a particular index in the registry has been set, use the static method isRegistered().
Example #8 Example of isRegistered() Method Usage
To find out if a particular index in a registry array or object has a value, use the isset() function as you would with an ordinary array.
The static registry is an instance of the class Zend_Registry. If you want to add functionality to the registry, you should create a class that extends Zend_Registry and specify this class to instantiate for the singleton in the static registry. Use the static method setClassName() to specify the class.
Note: The class must be a subclass of Zend_Registry.
Example #10 Example of Specifying the Singleton Registry's Class Name
The registry throws a Zend_Exception if you attempt to set the classname after the registry has been accessed for the first time. It is therefore recommended that you specify the class name for your static registry in your application bootstrap.
Although it is not normally necessary, you can unset the singleton instance of the registry, if desired. Use the static method _unsetInstance() to do so.
When you use _unsetInstance(), all data in the static registry are discarded and cannot be recovered.
You might use this method, for example, if you want to use setInstance() or setClassName() after the singleton registry object has been initialized. Unsetting the singleton instance allows you to use these methods even after the singleton registry object has been set. Using Zend_Registry in this manner is not recommended for typical applications and environments.
Example #11 Example of _unsetInstance() Method Usage