The primary reason you can’t use it on classes is that, when you do A + B, it should return a new instance, C. Now who’s responsible for freeing it? The semantics get really murky there.

There’s also the fact that Microsoft’s guidelines for operator overloading pretty much say, "Don’t do it for classes." See:

http://www.gotdotnet.com/team/fxcop/Docs/Rules/Design/DoNotOverrideOperatorEqualsOnReferenceTypes.html

http://www.gotdotnet.com/team/fxcop/Docs/Rules/DesignRules/AddAndSubNoEqualsOp.html

…and then apply the transitive property to those two rules. If you overload + and -, you should also overload =, which you shouldn’t do on reference types.

If you *really* want both operator overloading and classes for some reason, you could probably accomplish that by making a record type (with operator overloading) that wraps an interface reference (so you can do class-type stuff like inheritance).

Supported on record types only (see previous point)

:-((((((((((((((((((((((((((

…and classes????