Question

In Scala, I can define structural types as follows:

type Pressable = { def press(): Unit }

This means that I can define a function or method which takes as an argument something that is Pressable, like this:

def foo(i: Pressable) { // etc.

The object which I pass to this function must have defined for it a method called press() that matches the type signature defined in the type – takes no arguments, returns Unit (Scala’s version of void).

I can even use the structural type inline:

def foo(i: { def press(): Unit }) { // etc.

It basically allows the programmer to have all the benefits of duck typing while still having the benefit of compile-time type checking.

Does C# have something similar? I’ve Googled but can’t find anything, but I’m not familiar with C# in any depth. If there aren’t, are there any plans to add this?

Answer 1

No, and no plans that I know of. Only named (rather than structural) subtyping (e.g. interfaces).

(Others may want to see also

http://en.wikipedia.org/wiki/Nominative_type_system

http://en.wikipedia.org/wiki/Structural_type_system

)

(A few people may point out some exotic corner cases, like the foreach statement using structural typing for GetEnumerator, but this is the exception rather than the rule.)