Static Class Structure

• Context
  • Refers to the Strategy interface to perform an algorithm (strategy.algorithm())
    and is independent of how the algorithm is implemented.
  • Maintains a reference (strategy) to a Strategy object.
• Strategy
  • For all supported algorithms, defines a common interface for performing an algorithm.
• Strategy1,Strategy2,…
  • Implement the Strategy interface.

Dynamic Object Collaboration

• In this sample scenario, a Context object delegates performing an algorithm to different Strategy objects.
  Let's assume that Context is configured with a Strategy1 object.
• The interaction starts with the Context object that calls algorithm() on its installed Strategy1 object.
• Strategy1 performs the algorithm and returns the result to Context.
• Let's assume that Context changes its strategy to Strategy2 (because of run-time conditions such as reaching a threshold, for example).
• Context now calls algorithm() on the Strategy2 object, which performs the algorithm and returns the result to Context.
• There are different ways to select and change a strategy. For example, clients of Context might change the strategy or pass the strategy to the Context.
• See also Sample Code / Example 1.