Re: [boost] [xint] Third release is ready, requesting preliminary review

Subject: Re: [boost] [xint] Third release is ready, requesting preliminary review
From: DE (satan66613_at_[hidden])
Date: 2010-05-04 11:02:00

on 04.05.2010 at 18:54
 Jeffrey Lee Hellrung, Jr. wrote :

> On 5/4/2010 12:29 AM, DE wrote:
>> actually i don't see a reason to implement them that way
>> rather they should be implemented either of two ways
>>
>>    type operator@(type, const type&);
>>    type operator#(const type&, const type&);
>>
>> but not simultaneously
>> in the first case move semantics will take place where appropriate

> No good :(  Assuming only the *possibility* of reusing resources from 
> your arguments, you want the signature operator+(T,T) if you're adding 2
> rvalues, but the signature operator+(const T&, const T&) if you're 
> adding 2 lvalues (so you don't make unnecessary copies compared to 
> passing by value).  Unfortunately, you can't have both (ambiguous 
> overload resolution) :/  The only way to get something semantically 
> equivalent is to overload by rvalue reference.

> If reuse of resources is *unconditional*, then, sure, pass by value (as
> long as the swapping/moving is cheap).  If reuse of resources *never* 
> happens, then, sure, pass by reference-to-const.  Otherwise, the optimal
> approach is to provide all combinations of rvalue reference and lvalue
> reference-to-const parameters (in c++03).

sure you are absolutely right
i meant only the "unconditional" case

-- 
Pavel
P.S.
if you notice a grammar mistake or weird phrasing in my message
please point it out