Here there be tigers - operator overloading and conversions

MBA

MBA — Sat, 18 Dec 2004 18:53:00 GMT

Helpful For MBA Fans.

re: Here there be tigers - operator overloading and conversions

Keith — Mon, 22 Dec 2003 13:51:00 GMT

Joe,
You need to cast the null to either Object or String (I have a couple of cases in some uses of String.Format where I have this problem in addition to having to do it sometimes when using ? : notation. Well, it's not really a problem, since it is a very rare case for me that is an error not a warning, so I've never had an issue knowing which was going to be executed)

re: Here there be tigers - operator overloading and conversions

Eric — Tue, 16 Dec 2003 20:25:00 GMT

Joe,

I think that case falls out from the rules. There's an implicit conversion from null to object, and to string (by the reference conversion rules).

There's an implicit conversion from string to object, but not from object to string, so Process(string s) is better.

re: Here there be tigers - operator overloading and conversions

Joe McRay — Tue, 16 Dec 2003 20:08:00 GMT

Hi Eric!

class Utility
{
public void Process(object o);
public void Process(string s);
}

And what about
Utility.Process(null);
?

How does the compiler decide in this situation?
I think/know there must be rules, nevertheless I couldn't find any topic in the MSDN Lib (7.4.2.2). Maybe you can give me a hint.

Thx. Joe.

re: Here there be tigers - operator overloading and conversions

CausticMango — Fri, 12 Dec 2003 22:37:00 GMT

Hmm, good point. However, I'd have to question the intent for such an ambiguous overloading to begin with. It may be legitimate (aka a visitor implementation), but it's definitely suspicious.

There may be better ways to skin that cat (such as using the template method pattern and avoiding the ambiguous overload).