Is there a constraint that restricts my generic method to numeric types?

Question

Can anyone tell me if there is a way with generics to limit a generic type argument T to only:

• Int16
• Int32

Answer 1

This limitation affected me when I tried to overload operators for generic types; since there was no "INumeric" constraint, and for a bevy of other reasons the good people on stackoverflow are happy to provide, operations cannot be defined on generic types.

I wanted something like

public struct Foo
{
    public T Value{ get; private set; }

    public static Foo operator +(Foo LHS, Foo RHS)
    {
        return new Foo { Value = LHS.Value + RHS.Value; };
    }
}

I have worked around this issue using .net4 dynamic runtime typing.

public struct Foo
{
    public T Value { get; private set; }

    public static Foo operator +(Foo LHS, Foo RHS)
    {
        return new Foo { Value = LHS.Value + (dynamic)RHS.Value };
    }
}

The two things about using dynamic are

1. Performance. All value types get boxed.
2. Runtime errors. You "beat" the compiler, but lose type safety. If the generic type doesn't have the operator defined, an exception will be thrown during execution.