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MetaObject protocol

MetaObject are the object which are used to create the base objects. MetaObject used to manipulates, creates, describes or implements the other objects. MetaObject store the information in the base objects. The information metaobjects store must be object's type, interface, class, methods, attributes, parse tree. metaObject Protocol provides the commands to access and manipulate the structure and behavior of the objects. The functions of the metaobject protocol include:

Creating and deleting new classes
Creating new methods and properties
Changing the class structure so that classes inherit from different classes
Generating or modifying the code that defines the methods for the class

Commands of MetaObject

Commands	Discription
Object	Retrieves an attribute of an instance of the class
MetaMethod	Retrieves an instance MetaMethod for the given name and argument values
MetaProperty	Returns a MetaProperty for the given name or null if it doesn't exist
List<MetaMethod>	Obtain a list of all the meta methods available on this meta class
List<MetaProperty>	Obtain a list of all meta properties available on this meta class
Class	Sets an attribute of an instance of the class

When to use MetaObject protocol

Memoizing method calls
Complex inheritance (this may be of dubious value)
Loosening or strengthening a type system
Implementing Dynamic Dispatch (if necessary)
Persistence
Replication