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

On 01/03/17 13:14, Olaf van der Spek wrote:

On Sun, Jan 1, 2017 at 12:21 AM, Andrey Semashev wrote:

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If formatting is required I would prefer to be required to spell my intent more clearly, like this:

print(s, 47);

I'd expect print to output to cout.. wouldn't you? sprint then?

sprint works for me as well.

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Also, I'm not clear enough about the intended use cases of the proposed library. Is the goal just to optimize memory allocation?

No, the goal is also to provide a better and simpler way to handle integers.

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Is that at all possible when formatting is involved?

Yes, as manually calling reserve beforehand is always possible. How to optimally implement this is still an open question but that's kind of an implementation detail.

But you would have to either overallocate memory or perform the formatting to determine its length. And while overallocating might be possible for standard types such as integers and FP numbers (assuming C-locale format), that does not seem possible for user's types. Or are you not planning to support user-defined types?

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I think, something with one line capability like that would be useful. Would the library allow something like this?

Would the library support targets other than std::string?

Yes, probably.

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E.g. would I be able to format into an `std::array< char, 10 >`?

No, as array is fixed-size you can't append to it.. vector<char> might work though.

My intent was to format into a local/preallocated buffer, without any additional allocations, but I assume that won't work because `std::array` is lacking APIs for insertion. That probably means that you have to define a concept of the possible target, what operations it must support.