Prototype Pattern

The Prototype pattern allows an object to create customized objects without knowing their exact class or the details of how to create them. It specifies the kinds of objects to create using a prototypical instance and creates new objects by copying this prototype. The Prototype pattern works by giving prototypical objects to an object and then initiates the creation of objects. The creation-initiating object then creates objects by asking the prototypical objects to make copies of themselves. The Prototype pattern makes creating objects dynamically easier by defining classes whose objects can duplicate themselves. 

UML Representation


The following lists the benefits of using the Prototype pattern:
  • Adding and removing products at run time
  • Specifying new objects by varying values
  • Specifying new objects by varying structure
  • Reducing subclasses
  • Configuring an application with classes dynamically

When to Use

You should use the Prototype pattern when:
  • The classes to instantiate are specified at run time—for example,by dynamic loading
  • To avoid building a class hierarchy of factories that parallels the class hierarchy of products
  • When instances of a class can have one of only a few different combinations of state