As far as I can tell, this question is about run-time selection or mapping of one of several candidate Strategies. There’s no reason to rely on a DI Container to do this, as there are at least three ways to do this in a container-agnostic way: Use a Metadata Role Hint Use a Role Interface … 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
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
Scott Meyers in “Effective C++” item 42 says “Only inheritance gives access to protected members, and only inheritance allows for virtual functions to be redefined. Because virtual functions and protected members exist, private inheritance is sometimes the only practical way to express an is-implemented-in-terms-of relationship between classes.”
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
There are a few ways of doing this, but the way I prefer is to inject a list of available strategies into your factory, and then filtering them to return the one(s) you’re interested in. Working with your example, I’d modify IShippingStrategy to add a new property: public interface IShippingStrategy { int CalculateShippingCost(Order order); string … Read more
Let’s explain the strategy pattern the easy way: You have a class Car() with a method run(), so you use it this way in a pseudo language: mycar = new Car() mycar.run() Now, you may want to change the run() behavior on the fly, while the program is executing. For example, you might want to … 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