Re: [Boost-users] Why not overloading && and || in bind?

From: Jean-Pierre Bergamin (james_at_[hidden])
Date: 2008-02-18 14:49:03

Peter Dimov schrieb:
> Richard:
>   
>> [Please do not mail me a copy of your followup]
>>
>> boost-users_at_[hidden] spake the secret code
>> <011a01c87003$0ff77eb0$6407a80a_at_pdimov2> thusly:
>>
>>     
>>> [...] This thread did spark my interest though and I was able to add
>>> && and || to the trunk, complete with the proper short-circuit semantics.
>>>       
>> Can you elaborate on the approach you took?  I thought it was
>> essentially impossible to replicate the short-circuit semantics with
>> your own user-defined operator|| and operator&&.
>>     
>
> It is impossible to overload && in such a way so that in e1 && e2, e2 is not 
> evaluated when e1 is false. But it's possible to overload f && g so that in 
> (f && g)(x) :- f(x) && g(x), g(x) is not evaluated when f(x) is false. 
>   
Very nice. Your changes do the trick and we hopefully see the changes 
soon in an official release.

Thanks

Jean-Pierre Bergamin