Question

Can a method in C# return a method?

A method could return a lambda expression for example, but I don’t know what kind of type parameter could I give to such a method, because a method isn’t Type. Such a returned method could be assigned to some delegate.

Consider this concept as an example:

public <unknown type> QuadraticFunctionMaker(float a , float b , float c)
{
    return (x) => { return a * x * x  + b * x + c; };
}

delegate float Function(float x);
Function QuadraticFunction = QuadraticFunctionMaker(1f,4f,3f);

Answer 1

The Types you are looking for are Action<> or Func<>.

The generic parameters on both types determine the type signature of the method. If your method has no return value use Action. If it has a return value use Func whereby the last generic parameter is the return type.

For example:

public void DoSomething()                          // Action
public void DoSomething(int number)                // Action<int>
public void DoSomething(int number, string text)   // Action<int,string>

public int DoSomething()                           // Func<int>
public int DoSomething(float number)               // Func<float,int>
public int DoSomething(float number, string text)  // Func<float,string,int>