yank unary '+'?

[Andrei Alexandrescu]

Michel Fortin wrote:
> On 2009-12-07 01:29:14 -0500, Andrei Alexandrescu 
> <SeeWebsiteForEmail at erdani.org> said:
> 
>> Using double negation !!x throughout, there are only advantages and no 
>> disadvantage. I hit that design with Pacquiao punches over the past 
>> week or so, and couldn't find any shortcoming. It's consistent across 
>> positive and negated uses, easy to understand, easy to define, 
>> consistent with built-in types, and Walter likes it.
> 
> I'm not sure that's a great idea. What if you define your own FuzzyBool 
> type (containing some sort of probability) and FuzzyBool.opUnary!("!") 
> returns an inverted FuzzyBool (with 1 - original probability) instead of 
> a regular bool, you'd have an infinite loop trying to evaluate 
> !!myBoolValue.

Yeah, I thought about that liability and decided to discount it as a 
design mistake of the user. If a type decides to return non-bool from 
"!", they are bound to unpleasantly surprise its user in more ways than 
one. You can define a negate for FuzzyBool - just don't dress it as the 
"!" operator.

Andrei