Strategy

Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithms vary independently from clients that use it.

Applicability

• Need many related classes that differ only in their behavior
• Need different variants of an algorithm
• Need to hide algorithm data from the clients
• A class defines many behaviors and these appear as multiple conditional statements in its operations. (See also State.)

Consequences

• Families of related algorithms
• An alternative to subclassing the Context
• Strategies eliminate conditional statements
• Allow choice of implementation
• Clients must be aware of different strategies
• Communication overhead between Strategy and Context may be high
• Increased number of objects