Markus fdb9be1e76 Work towards #56: Add permalink to every pattern
This makes cleaner URLs thanks to jekyll
2015-08-15 18:03:05 +02:00

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---
layout: pattern
title: Strategy
folder: strategy
permalink: /patterns/strategy/
categories: pattern_cat
tags: pattern_tag
---
**Intent:** Define a family of algorithms, encapsulate each one, and make them
interchangeable. Strategy lets the algorithm vary independently from clients
that use it.
![alt text](./etc/strategy_1.png "Strategy")
**Applicability:** Use the Strategy pattern when
* many related classes differ only in their behavior. Strategies provide a way to configure a class either one of many behaviors
* you need different variants of an algorithm. for example, you might define algorithms reflecting different space/time trade-offs. Strategies can be used when these variants are implemented as a class hierarchy of algorithms
* an algorithm uses data that clients shouldn't know about. Use the Strategy pattern to avoid exposing complex, algorithm-specific data structures
* a class defines many behaviors, and these appear as multiple conditional statements in its operations. Instead of many conditionals, move related conditional branches into their own Strategy class