Opinions needed on neg and absolute

[Paul C. Anagnostopoulos]

At 8/30/2010 07:12 PM, Joshua Juran wrote:
>On Aug 30, 2010, at 3:45 PM, Paul C. Anagnostopoulos wrote:
>
>>As an example of a PMC that inherits from Integer and might rely on  
>>the current behavior, I give you Boolean. It inherits 'neg' and  
>>relies on the fact that it does not promote to implement the  
>>following bizarre behavior:
>>
>>-(Boolean true) => true
>>-(Boolean false) => false
>>
>>I will simply implement 'neg' in Boolean to preserve this whackiness.
>
>What's so odd about that?  If you think of 'false' as zero, then the  
>inverse of zero equals zero (false) and the inverse of any non-zero  
>integer is non-zero (true, e.g. 1 -> -1).  Though if Boolean is a one- bit integer, it must be an unsigned type, and -true will wrap around  
>to true anyway.

I don't think of booleans as integers, so negating them is incoherent. But let's not get into that religious war.

I agree that if you think of 0 as false and everything else as true, then negating a boolean should not change its value. But providing negation for booleans is just another way to end up with obscure and possibly buggy code.

~~ Paul
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