Question

I have a very thin interface that’s going to define one method. Should I require the type parameter on the class definition?

public interface ISomethingFun<T> {     void Do(T item); } 

or method definition?

public interface ISomethingFun {     void Do<T>(T item); } 

What rationale? Is one easier to implement, inherit, or generate dynamically? Is it style? Is there some OO guidance that applies?

Answer 1

The advantage to having the generic on the method is that it facilitates type inference.

void Example(ISomethingFun fun) {   fun.Do(42); } 

There you go, a completely generic call, no generic parameters. Putting the generic Parameter on the type forces you to add generic signatures or bindings whenever the type is shown in metadata

void Example2<T>(ISomethingFun<T> fun) { ... } 

This is not necessarily a bad thing and is in fact often necessary. It’s just a difference.

In general though, if every method has the same generic parameter, just add it to the type 🙂