Typically the Command pattern is used to make an object out of what needs to be done — to take an operation and its arguments and wrap them up in an object to be logged, held for undo, sent to a remote site, etc. There will tend to be a large number of distinct Command … Read more
What about this: You have to encrypt a file. For small files, you can use “in memory” strategy, where the complete file is read and kept in memory ( let’s say for files < 1 gb ) For large files, you can use another strategy, where parts of the file are read in memory and … Read more
DI and Strategy work in the same way, but Strategy is used for more fine-grained and short-lived dependencies. When an object is configured with a “fixed” Strategy, for example when the object is constructed, the distinction between Strategy and DI blurs. But in a DI scenario it is more unusual that the dependencies of objects … Read more
I’m including an encapsulation hierarchy table of several of the GoF design patterns to help explain the differences between these two patterns. Hopefully it better illustrates what each encapsulates so my explanation makes more sense. First off, the hierarchy lists the scope for which a given pattern is applicable, or the appropriate pattern to use … Read more
Semantics. From wikipedia: The UML class diagram for the Strategy pattern is the same as the diagram for the Bridge pattern. However, these two design patterns aren’t the same in their intent. While the Strategy pattern is meant for behavior, the Bridge pattern is meant for structure. The coupling between the context and the strategies … Read more
A factory pattern is a creational pattern. A strategy pattern is an operational pattern. Put another way, a factory pattern is used to create objects of a specific type. A strategy pattern is use to perform an operation (or set of operations) in a particular manner. In the classic example, a factory might create different … Read more
The template pattern is used when a particular operation has some invariant behavior(s) that can be defined in terms of other varying primitive behaviors. The abstract class defines the invariant behavior(s), while the implementing classes defined the dependent methods. In a strategy, the behavior implementations are independent — each implementing class defines the behavior and … Read more
Honestly, the two patterns are pretty similar in practice, and the defining difference between them tends to vary depending on who you ask. Some popular choices are: States store a reference to the context object that contains them. Strategies do not. States are allowed to replace themselves (IE: to change the state of the context … Read more