为什么 C# 运算符重载必须是静态的？

Question

Why does C# require operator overloads to be static methods rather than member functions (like C++)? (Perhaps more specifically: what was the design motivation for this decision?)

Answer 1

This has been answered in excruciating detail by Eric Lippert in a blog post that has since been removed. Here is the archived version .

There is also another subtler point about value types and instance operators. Static operators make this kind of code possible:

class Blah {

    int m_iVal;

    public static Blah operator+ (Blah l, int intVal)
    {
        if(l == null)
            l = new Blah();
        l.m_iVal += intVal;
        return l;
    }
}

//main
Blah b = null;
b = b + 5;

So you can invoke the operator, even though the reference is null. This wouldn't be the case for instance operators.

Answer 2

Take a look at this post .

A couple of reasons, the primary seeming to be to preserve operator symmetry (such that the left hand side of a binary operation does not get special treatment, as being responsible for dispatching the operation).

Answer 3

Perhaps its best to think why should the methods not be static. There is no need for state and hence this.