On Mon, Mar 23, 2009 at 6:32 PM, Nicolas Cellier <
nicolas.cellier.aka.nice at gmail.com> wrote:

> 1) #xor: should not take a block as argument.
> Rationale:
> - the block would ALWAYS have to be evaluated
> - block arguments are either for repeated evaluation, or condiitonal
> evaluation...
> This is not the case here, so the need of a block argument vanishes...
>
> 2) #xor: argument should be a Boolean, but here no guard is made.
>
> We could eventually add:
>    aBoolean isBoolean ifFalse; [self error: 'xor must take a boolean as
> argument']
>
> Or if we want to later extend to some other class:
> True>>xor: aBoolean
>     ^aBoolean xorTrue
> False>>xor: aBoolean
>     ^aBoolean xorFalse
> True>>xorTrue
>     ^false
> True>>xorFalse
>     ^self
> False>>xorTrue
>     ^true
> False>>xorFalse
>     ^self


I think just

True>>xor: aBoolean
    ^aBoolean not

False>>xor: aBoolean
    ^aBoolean

and then leave subsequent usage to catch possible type errors; e.g. (false
xor: #blah) ifTrue: ... will raise a mustBeBoolean error.


MySymbolicBooleanClass>>xorTrue
>     ^SymbolicXorOperation with: self with: true
>
> I'm not sure whether we need to protect or not...
> I tend to avoid over-protecting code. As long as a debugger opens, I claim
> protecting is void...


+1


>
> But here, I don't like a false program proceeding without a Notifier....
>
> Nicolas
>
> 2009/3/24 Keith Hodges <keith_hodges at yahoo.co.uk>
>
>> true xor: [ true ]  => true
>>
>> discuss
>>
>> Keith
>>
>>
>>
>>
>
>
>
>
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