Re: [boost] rvalue ref best practices?

Subject: Re: [boost] rvalue ref best practices?
From: Gpderetta (gpderetta_at_[hidden])
Date: 2012-06-13 15:44:07

(i know i have been advocating pass-by-value, but....)

On 13/giu/2012, at 19.41, Nevin Liber <nevin_at_[hidden]> wrote:

> On 12 June 2012 18:08, Ion Gaztañaga <igaztanaga_at_[hidden]> wrote:
>
>> If I modify my implementation because I no longer need the internal  
>> copy
>> (e.g. the copy was required by an internal function/helper  
>> function), I
>> can't optimize the code and change the signature of the function to  
>> take a
>> reference, as name mangling changes and I'll need to recompile the  
>> caller.
>> If I offer both lvalue and rvalue reference variants I type a bit  
>> more but
>> I can safely change the implementation.
>
>
> On 13 June 2012 12:48, Mathias Gaunard <mathias.gaunard_at_ens- 
> lyon.org> wrote:
>
>> On 06/13/2012 04:12 PM, Peter Dimov wrote:
>>
>> Or 2^N overloads, if there's more than one argument to consume.
>>>
>>
>> In which case, make your constructor a template so that all those
>> overloads get generated through template instantiation, making use  
>> of the
>> template type resolution mechanism specifically designed for perfect
>> forwarding.
>>
>
> But if your constructor is a template, that code resides in the  
> header, so
> don't you end up recompiling the caller anyway?

You can have a thin template forwarding to a single  externally  
compiled implementation using for example rvalue references for all  
parameters. The template would copy or move depending on the actual  
parameter type.

-- gpd