Is the strategy template a violation of the principle of shared responsibility?

Question

If the Single Responsibility Principle states that each object should have one reason for change, and one strategy class implemented in the strategy template (by definition) has several methods that can change for any reason, does this mean that Is it impossible to implement a strategy template without breaking SRP?

Answer 1

How so? The strategic pattern, if I recall, is basically a way of decoupling the logic / algorithm used. Thus, the client has m_IAlgorithm. IAlgorithm should have a small set of methods, if not one.

So the only reason the AlgoImplementation class can change is because

• if there is a change in the algorithm that it implements. ( change of his responsibility / behavior )
• or if IAlgoritm .. changes, which would be rare if you were not mistaken in defining the interface. (Its change in its own public interface - so don't think it's an SRP violation.)

Answer 2

I really see the opposite. The strategy template allows you to separate two things, (potential) algorithms used to perform specific work and decision logic about these algorithms.

I'm not sure if you have a class that executes both the conditional logic on which the algorithm should use, and covers these algorithms. Besides, I’m not saying that you meant it, but you didn’t give an example when the strategy broke SRP and, in your opinion, the best design.

Answer 3

The context that I am most familiar with the principle of shared responsibility is the overall design of the system and can complement the strategic pattern regarding the grouping of components within the system.

Use the strategy template to determine the set of algorithms that the client uses interchangeably, then the principle of single responsibility can be used to determine where to group the client and the algorithms that the client uses in the system. You do not want to break the code of algorithm A if your work is performed exclusively in algorithm B and vice versa. For compiled languages, this can have a significant impact on the complexity of the re-factor cycle, version, and deployment. Why version and recompile the client and algorithms A, C and D when the only changes needed for algorithm B.

With this understanding of the principle of shared responsibility, I do not see that if a class that implements a strategy template violates SRP. The purpose of the customer class is to implement a strategy template, that is, customer responsibility. The purpose of the algorithms is to implement the logic for which they are responsible, and the principle of shared responsibility says that they do not group them together within the system, since they will change for various reasons. This is my $ 0.02.

Answer 4

Good point :) I guess this is more than one guide that makes sense for many cases, but for some it also doesn't, like a strategy template.