A registry is a global association from keys to objects, allowing the objects to be reached from anywhere. It involves two methods: one that takes a key and an object and add objects to the registry and one that takes a key and returns the object for the key. It's similar to the MultitonPattern, but doesn't restrict instances to only those in the registry.

See also:

* http://martinfowler.com/eaaCatalog/registry.html
* http://www.phppatterns.com/index.php/article/articleview/75/1/1/, for an example of a Singleton Registry in PHP

Also Known As:
* GlobalVariable''''''s
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CategoryPattern