C#/.NET: Is `typeof(variable)` a possible language feature?

Question

On a few separate occasions, I have tried to coax the declared type out of a variable, relatively far from its declaration, only to find out that typeof(T) only works on type names.

I was wondering if there would be any breaking changes to allow typeof(variable) as well.

For example, with this code:

class Animal { /* ... */ }
class Goat : Animal { /* ... */ }

/* ... */

var g = new Goat();
Animal a = g;

Console.WriteLine(typeof(Goat));
Console.WriteLine(typeof(Animal));
Console.WriteLine(g.GetType());
Console.WriteLine(a.GetType());

You get something like:

Goat
Animal
Goat
Goat

Why is it not possible to do this:

Console.WriteLine(typeof(g));
Console.WriteLine(typeof(a));

Goat
Animal

I have given the spec a cursory glance, and can't find any conflict. I think that it would clear up the question 'Why this type?' when using the typeof operator.

I know that the compiler is capable, here. An implementation using extension methods is actually trivial:

public static Type TypeOf<T>(this T variable)
{
    return typeof(T);
}

But that feels dirty, abusing the type-inference of the compiler.

Answer 1

I think the problem here is that .GetType() is older than typeof(). There used to be a day in C# where you needed to do

"0".GetType()

in order to get the String type (for example), until typeof() was born. I think if the concept had been part of the original language design, then indeed it might work as you describe. Due to typeof() being a late introduction to the language, then the designers had to make a choice: Obsolete/deprecate/remove .GetType() (and in the process make many, many uses of it obsolete), make typeof() overlap in functionality with GetType() (which is what you are asking), or make typeof()'s usage not overlap with GetType(). I think the C# people simply chose not to make the functionality overlap (to keep things simple and clear), and so typeof() was restricted in the way it is today.