Re: [boost] Variadic append for std::string

Subject: Re: [boost] Variadic append for std::string
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2016-12-29 08:53:48

On 12/29/16 11:54, Olaf van der Spek wrote:
> On Thu, Dec 29, 2016 at 1:19 AM, Yakov Galka <ybungalobill_at_[hidden]> wrote:
>> On Tue, Dec 27, 2016 at 4:47 PM, Olaf van der Spek <ml_at_[hidden]> wrote:
>>
>>> One frequently needs to append stuff to strings, but the standard way
>>> (s += "A" + "B" + to_string(42)) isn't optimal due to temporaries.
>>>
>>
>> Can't we already write it through (((s += "A") += "B") += to_string(42))?
>> This is the time I think that assignment operators, other than =, should
>> have had left associativitiy... pity they don't.
>
> We can, but it's ugly and I'd like to avoid the explicit to_string. It
> also wouldn't allow the two-pass optimization to calculate the final
> length before allocation.

I already mentioned in the std-proposals discussion that I don't think 
formatting should be dealed with by std::string or a function named 
append(). If formatting is to be involved I'd suggest creating a 
formatting library, but at that point you should provide clear 
advantages over the other formatting libraries we have in Boost.