Explain Registry pattern in Magento?

Registry pattern is basically a pattern that allows any object or data to be available in a public global scope for any resource to use.

In Magento, you can register an object or data with Mage::register function,

Mage::register('identifier', $object_or_data);

After it is registered, you can call it with Mage::registry by passing identifier name:

Mage::registry('identifier');

You can also unregister an object at any time with Mage::unregister

Mage::unregister('identifier');

This is especially helpful transferring data between Models and Blocks without having to instantiate an entire class and load data.

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