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

Subject: Re: [boost] Variadic append for std::string
From: Olaf van der Spek (ml_at_[hidden])
Date: 2017-01-11 10:03:36

On Wed, Jan 11, 2017 at 10:02 AM, Christof Donat <cd_at_[hidden]> wrote:

> Hi,
>
> Am 11.01.2017 09:28, schrieb Olaf van der Spek:
>
>> On Tue, Jan 3, 2017 at 4:55 PM, Christof Donat <cd_at_[hidden]> wrote:
>>
>>> I know, but you came up with C++ beginners. They already often get
>>> confused
>>> with streams and bit shifts, mostly when they come to C++ from C. Now we
>>> additionally mix expressions, where we can use manipulators with those,
>>> where we can't. That will probably make things worse not only for C++
>>> beginners.
>>>
>>
>> Maybe, maybe not.
>> Overloading yet another operator for a similar (but not equal) purpose is
>> problematic too.
>>
>
> That is true. Actually I think, the best option is a different class, that
> behaves just like a stream. Then it'll support manipulators, etc. No one
> will be surprised, that strings behave similar to streams, but not really
> the same, etc. We already have that class in the standard library:
> std::ostringstream.
>
> BTW: boost::format follows that same pattern as well. It just doesn't use
> the shift operator to prevent confusion with stream.
>
> I think << is quite elegant.
>>>
>>>>
>>>>
>>> I feel very uneasy with it and I think I have presented quite some
>>> reasoning why.
>>>
>>
>> You have, but I don't think we have a significantly better alternative.
>>
>
> The significantly better alternative is std::ostringstream. I think our
> debate showed very nicely, that all the options, we have come up with to
> simplify the concatenation of strings are significantly inferior in total,
> though we could find examples, where they slightly improve readability.

Interface is important, as is performance.. and performence of
ostringstream sucks..

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0067r1.html
https://gist.github.com/anonymous/7700052

-- 
Olaf