Software Architecture Design Patterns in Java

32 MEMENTO

This pattern was previously described in GoF95.

DESCRIPTION

The state of an object can be defined as the values of its properties or attributes at any given point of time. The Memento pattern is useful for designing a mechanism to capture and store the state of an object so that subsequently, when needed, the object can be put back to this (previous) state. This is more like an undo operation. The Memento pattern can be used to accomplish this without exposing the object’s internal structure. The object whose state needs to be captured is referred to as the originator. When a client wants to save the state of the originator, it requests the current state from the originator. The originator stores all those attributes that are required ...