Hi again Jonny,

just to come back to your original example and to clearify things:
std::format is supposed to replace not only your missing
"to_string(bool)" but to process the entire formatting in your example.
So you example might become:

std::string fmt(const std::string header, bool b)
{
   return std::format("{} {} set", header, b);
}

Cheers,
Sebastian

On 2019-07-21 00:03, Sebastian Büttner via Std-Proposals wrote:
> Hi Jonny,
>
> std::format origins from libfmt (https://github.com/fmtlib/fmt/). The
> syntax is related to other format libraries that have prooven useful
> like pythons string.format for example.
>
> The main goal is to get the typesafety from iostreams but the
> convenient format strings of printf like approaches.
>
> Booleans are by default formatted with their textual representation
> (true|false), so the following is sufficient:
>
> std::string s = std::format("{}", true);
>
> which is kinda neat :) (you do not need type information within the
> formatting string which is great for typesafety!)
>
> Cheers,
> Sebastian
>
> On 2019-07-20 23:51, Jonny Grant via Std-Proposals wrote:
>
>> Hi Garrett
>>
>> Many thanks for the reply with link.
>>
>> std::format could be good good, I hadn't heard. Currently I had always
>> needed to use my own variadic std::string str_sprintf().
>> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0645r9.html#Syntax
>>
>> Saw this
>> std::string s = std::format("{:s}", true);
>>
>> It looks like different syntax to printf % style is being used. Don't
>> think that is ideal...
>> But at least bool is in..
>>
>> Cheers, Jonny
>>
>> On 20/07/2019 22:24, Garrett May via Std-Proposals wrote:
>>
>> Hi Jonny,
>>
>> With respect to std::to_string, please see a reference to it here:
>> https://en.cppreference.com/w/cpp/string/basic_string/to_string
>>
>> std::to_string appears to be defined specifically for primitive
>> numeric types that match up to using sprintf and a format specifier. I
>> don't think that std::to_string(bool) would be suitable, as it does
>> not have a format specifier like the others. And there is also the
>> possibility that when converting a bool to a string that the user
>> genuinely want '0' or '1' to be produced, as they may be trying to
>> handle the result as data.
>>
>> As Jake said, there is a format library coming out for C++20. That
>> sounds like a more desirable way to handle this problem, as like I
>> mentioned, choosing how one wants a bool to be represented textually
>> is similar to how one would want a float or a double represented
>> textually.
>>
>> Regards,
>>
>> Garrett
>>
>> On Sat, 20 Jul 2019, 21:39 Jonny Grant via Std-Proposals,
>> <std-proposals_at_[hidden]> wrote:
>> Hi Garrett
>>
>> Many thanks for your reply.
>>
>> Yes, I see std::boolalpha sets an I/O flag.. but seems a bit of a long
>> way to get it into a string, I'd need to use in conjunction with
>> std::istringstream to get a string...
>>
>> I wanted to do something like this example:
>>
>> IDEA
>> std::string fmt(const std::string header, bool b)
>> {
>> return header + " " + std::to_string(b) + " set";
>> }
>>
>> HOW I WOULD DO NOW
>> As his doesn't work, I'd have it at present as:
>> std::string fmt(const std::string header, bool b)
>> {
>> return header + " " + b?"true":"false" + " set";
>> }
>>
>> Regards, Jonny
>>
>> On 20/07/2019 21:21, Garrett May via Std-Proposals wrote:
>>
>> std::boolalpha is already available:
>>
>> int main(){
>> bool const a = true;
>> std::cout << std::boolalpha << a << std::endl;
>> }
>>
>> My gut instinct here is that one is supposed to control how one wants
>> data to be printed out, in the same way as how float/double precision
>> is done.
>>
>> On Sat, 20 Jul 2019, 21:16 Jonny Grant via Std-Proposals,
>> <std-proposals_at_[hidden]> wrote: Hello
>>
>> Could std::string to_string(bool value); be added? Currently it
>> outputs
>> as a number due to the implicit conversion to int?
>> Feel it would have been more appropriate as "true" or "false".
>>
>> http://www.cplusplus.com/reference/string/to_string/
>>
>> $ g++-8 -Wall -o to_string to_string.cpp
>> $ ./to_string
>> 1
>>
>> // g++-8 -Wall -o to_string to_string.cpp
>> #include <string>
>> #include <iostream>
>> int main()
>> {
>> const bool a = true;
>> const std::string b(std::to_string(a));
>> std::cout << b << std::endl;
>> }
>>
>> Cheers, Jonny
>>
>> .
>>
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