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 03:28:44

On Tue, Jan 3, 2017 at 4:55 PM, Christof Donat <cd_at_[hidden]> wrote:

> Hi,
>
> Am 03.01.2017 16:08, schrieb Olaf van der Spek:
>
>> How about this one?
>>>>
>>>> throw std::runtime_error("Error "s << 47);
>>>>
>>>
>>>
>>> Uh. How does that work with
>>>
>>>   std::cout << "Error "s << 47;
>>>
>>> Will that be
>>>
>>>   (std::cout << "Error "s) << 47;
>>>
>>> or
>>>
>>>   std::cout << ("Error "s << 47);
>>>
>>
>> We've got rules for that..
>> http://en.cppreference.com/w/cpp/language/operator_precedence
>>
>
> 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.

> 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.

> Also I don't seem to be the only one in this discussion.
> At least that should count as a strong indicator, that you need much
> better reasons to back your proposal.

-- 
Olaf