Question

This is mot likely a duplicate, but I couldn’t find a proper question.

I want to get "MyClass.Name" from () => MyClass.Name. How do I define the method parameter and how do I convert the expression to a string?

Answer 1

That is an Expression<Func<string>>, so you could have:

void Foo(Expression<Func<string>> selector) {...}

or

void Foo<T>(Expression<Func<T>> selector) {...}

however, note that the syntax MyClass.Name refers to a static property; if you want an instance property you might need something more like an Expression<Func<MyClass,string>> – for example:

static void Foo<TSource, TValue>(
    Expression<Func<TSource, TValue>> selector)
{

}
static void Main() {
     Foo((MyClass obj) => obj.Name);        
}

As for implementation; in this simple case, we can expect the Body to be a MemberExpression, so:

static void Foo<TSource, TValue>(
    Expression<Func<TSource, TValue>> selector)
{
    var member = ((MemberExpression)selector.Body).Member;
    Console.WriteLine(member.ReflectedType.Name + "." + member.Name);
}

However, it is more complex in the general case. This will also work if we use the static member:

static void Foo<TValue>(
    Expression<Func<TValue>> selector)
{
    var member = ((MemberExpression)selector.Body).Member;
    Console.WriteLine(member.ReflectedType.Name + "." + member.Name);
}