Can we restrict the type be a delegate [duplicate]

Question

We can restrict the type be the class or struct. Can we strict the type be a delegate?

Answer 1

A Delegate is a class, and you would normally be able to specify a non-sealed class as a constraint. However, the language specification specifically excludes System.Delegate as a valid constraint in section 10.1.5.

A class-type constraint must satisfy the following rules:

• The type must be a class type.
• The type must not be sealed.
• The type must not be one of the following types: System.Array, System.Delegate, System.Enum, or System.ValueType.
• The type must not be object. Because all types derive from object, such a constraint would have no effect if it were permitted.
• At most one constraint for a given type parameter can be a class type.