220 36856 <4bce681e-e729-4124-9322-69291fdb6678@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: inkwizytoryankes@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: String interpolation Date: Fri, 9 Feb 2018 14:12:26 -0800 (PST) Lines: 289 Approved: news@gmane.org Message-ID: <4bce681e-e729-4124-9322-69291fdb6678@isocpp.org> References: <356d5835-f1bf-4699-94f5-0b2d3d0b9c0e@isocpp.org> <25CCF885-86AD-4D51-8F5C-C46376D34DE0@gmail.com> <4890431.TR9UepuQra@tjmaciei-mobl1> <1cdb6300-7397-46d7-bce9-62e6e8dac40b@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_2334_264573856.1518214346871" X-Trace: blaine.gmane.org 1518214245 8281 195.159.176.226 (9 Feb 2018 22:10:45 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 9 Feb 2018 22:10:45 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDDLTAGNTIBBBS5Z7DJQKGQEUDUJXTI@isocpp.org Fri Feb 09 23:10:41 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f197.google.com ([209.85.217.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1ekGsB-0000ru-FF for gclcip-std-proposals@m.gmane.org; Fri, 09 Feb 2018 23:10:23 +0100 Original-Received: by mail-ua0-f197.google.com with SMTP id k4sf5762321uad.13 for ; Fri, 09 Feb 2018 14:12:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=XoDkORy+CrtD+vvnp7so4ko4Wa42BRqgBZpLW/EW4hM=; b=FAslg7/JXF9Lj0vmxC0BLe+QfchKgICpgVDRhj7x5/O0ZQShdx2yOtiWynCDyOm/eI R8/7ayyK9QhVd5ck7SsMrr6YSCDDNv53gdunZmsznsjbSNwJuG3v+PwTNfKB+TlU4rMM gYgEIPmndVWXvcIaQVrymgbylwmZn+ezLnzkrTD/eFEPT+nwRigw2VfTTXD4X06atF6E JX7jUO9W+xa7RPzGnst7chtypsO7HEQnyDpseBfqv/o/myiIFYek4UyfyqnG2mnV7GK9 jKi/Y1O8mkTk4P/hb2sFo2w+jlidV5nKF0j7h2K+lm8vgcbqaJqtAKy8QPPNNlxY5Fd1 M4UA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=XoDkORy+CrtD+vvnp7so4ko4Wa42BRqgBZpLW/EW4hM=; b=lVeMJnSc2vTal7hCf5jtDls3e+/dCV6zNTTtR+ACGLcqXnjRWgpXQcKmgvU1vxxPRA AWbjshNukP9lYlEK2inGGtB89qtrZCvUPqVX/MCXFnLB0My4Hz5HpQeodU/KwoycQlrj nIklFc9qH8SQqvx4xplPC/rMxQf2RQy0Cg6Vm2ohc4tdSaY+0n89c15SD2tWSl1nmVXh 453VzOOm/6DFcc+qPQQuw/7C+uu0iccGvsV2O57WTb+wFXQH3LhXU9Nj8S+AVOPFzDAN sICOhjFkNXOpsi/A0ppmzqdnS4Rie7BJhDdJZSA0ijNR8kySOR2vXNr/HGnHQUmVBEvf 9E4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=XoDkORy+CrtD+vvnp7so4ko4Wa42BRqgBZpLW/EW4hM=; b=iTRRi7QuoFqGF6/gkhDqgyQ695wRACL9tBUEUpZfoVVptW8iKJAC/1sIPd+1TyLn3h PkATq0+MOo4xV+qND6Sw/qJkL3QRJjrRNNoke6JsO/JpMzIGl99v5YagHNuqnqouYeXK 0FUr8S3inSG6KHKOxxGAR05aHdWIokUp6NoMPX18jc3AONfMZTvuKfPHQ+xYrX0wwNpc TBi3jXpmlRot7L/p4R3ix6X2Das25D889ZJY+8ceYAY3a/3TbItzTpd5/TJLQ5x+u494 MF+SqxUfoEl9EjxD9kGk8R1u+f4FVtNFvLd5eXgaQkF6HzphPE6sdofZ9cJw2Uz5dA2a MUMw== X-Gm-Message-State: APf1xPA3PKsOtqH8kdvsMqQTGh/vzo/nWDIQR9Pexzt0NzvTfVSETEbM fOCe9XhpzBsE7g9MEY539ynMjw== X-Google-Smtp-Source: AH8x224KAUCVdNPpWMT1349R8QN6garZuU6cUyhTpLYI6KFaIi4ZvsmSNDjSGMZmzlO1v9FrSxRfiQ== X-Received: by 10.176.96.10 with SMTP id j10mr2199214ual.40.1518214349024; Fri, 09 Feb 2018 14:12:29 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.31.7.13 with SMTP id 13ls4373472vkh.12.gmail; Fri, 09 Feb 2018 14:12:27 -0800 (PST) X-Received: by 10.31.41.214 with SMTP id p205mr375840vkp.13.1518214347342; Fri, 09 Feb 2018 14:12:27 -0800 (PST) In-Reply-To: X-Original-Sender: inkwizytoryankes@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:36856 Archived-At: ------=_Part_2334_264573856.1518214346871 Content-Type: multipart/alternative; boundary="----=_Part_2335_1613922253.1518214346872" ------=_Part_2335_1613922253.1518214346872 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Friday, February 9, 2018 at 10:13:10 PM UTC+1, Jake Arkinstall wrote: > > > > On 9 Feb 2018 20:51, > wrote: > > > Minimal version than could be added to C++ is new string prefix `F`=20 > (because we have `R`, `u`, `u8` and `U` already, and `$` is outside of=20 > source characters) that enable mixing code with string literals. > As Marcel Kr=C3=BCger wrote, language could transform this string literal= to: > F"testA{a}test{{B}}"_x; =3D> operator""_x("testA"_x, a, "test{B}"_x); //u= sing=20 > same postfix to parse sub-literals > FR"aa(x{b}y)aa"_x; =3D> operator""_x(R"aa(x)aa"_x, b, R"aa(y)aa"_x); //it= =20 > have precedence over `R` prefix > > > > Rest will be implemented by library, this mean `F"a {5} b"` will not=20 > compile because there is no matching operator. stl could add this operato= r=20 > for `s` postfix, that will use `std::to_string` for conversing all=20 > arguments: > template > std::string operator""s(Parts&&... p) { return std::to_string(std::forwar= d > (p)) + ...; } > > int main() > { > auto x =3D F"Test {{a}} =3D {10+5}"s; //x =3D=3D "Test {a} =3D 15"s > } > No iosteam, and even more it could if someone relay desire to have=20 > localizations: > > F"Test {356*10}"_loc("Prod {0} OK!", "fr") =3D=3D "Prod 3.560,00 OK!"; > > Only drawback is some template bloat but this is probably acceptable cost= .. > > > This is exactly the kind of thing I'm aiming for, although I dont believe= =20 > string conversion and concatenation to be the final solution - unless my= =20 > recall of benchmarks is out of date, streams are faster than string=20 > concatenation. > > This being said, similar ideas can be applied to utilise the fmt library,= =20 > for example. > =20 This is irrelevant, how it will be implemented is QoI, It could be done=20 using `snprintf`, or even not implemented at all, only prefix `F`and its=20 transformation is important. More I think about this more it look as great addition to language: std::string a; int b =3D 0; int c =3D 42; db.run(F"select name as {a}, age as {b} from table where id =3D {c}"_sql); auto i =3D 1; auto j =3D 3; FR"( set x =3D {i}; set b =3D {j}; set {i} =3D 3 * x + b + b; )"_script; assert(i =3D=3D 9); F"Log %f{3.5f} %3f{100f} %d{5}"_printf; // equal to printf("Log %f %3f %d",= =20 3.5f, 100f, 5) --=20 You received this message because you are subscribed to the Google Groups "= ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/4bce681e-e729-4124-9322-69291fdb6678%40isocpp.or= g. ------=_Part_2335_1613922253.1518214346872 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Friday, February 9, 2018 at 10:13:10 PM UTC+1, = Jake Arkinstall wrote:


On 9 Feb 2018 20:51,= <inkwizyt...@gmail.com> wrote:

Minimal version than could be added to C++= is new string prefix `F` (because we have `R`, `u`, `u8` and `U` already, = and `$` is outside of source characters) that enable mixing code with strin= g literals.
As Marcel Kr=C3=BCger wrote, language could transform this s= tring literal to:
F"testA{a}te= st{{B}}"_x; =3D> operator""_x("testA"_x, a, "test{B}"_x); <= span style=3D"color:#800">//using same postfix to parse sub-literals=
FR"aa= (x{b}y)aa"_x; =3D> operator""_x(R"aa(x)aa"_x, b, R"aa(y)aa"= ;_x); //it hav= e precedence over `R` prefix



Rest will= be implemented by library, this mean `F"a {5} b"` will not compi= le because there is no matching operator. stl could add this operator for `= s` postfix, that will use `std::to_string` for conversing all arguments:
template<typename... Parts>
std::string operator""s(Parts&&... p) = { return std::to_string(std<= span style=3D"color:#660">::forward<Part= s>(p= )) + ...; }

int main<= span style=3D"color:#660">()
{
=C2=A0 =C2= =A0 auto x =3D= F"Test {{a}} =3D {10+5}"s; //x =3D=3D "= Test {a} =3D 15"s
}
No iosteam, and even more it could if someone relay desire t= o have localizations:

=
F"Te= st {356*10}"_loc("Prod {0} OK!"= , "fr") =3D= =3D &qu= ot;Prod 3.560,00 OK!";

Only drawback is some= template bloat but this is probably acceptable cost.

T= his is exactly the kind of thing I'm aiming for, although I dont believ= e string conversion and concatenation to be the final solution - unless my = recall of benchmarks is out of date, streams are faster than string concate= nation.

This being said,= similar ideas can be applied to utilise the fmt library, for example.
=C2=A0
This is irrelevant, how it will be imple= mented is QoI, It could be done using `snprintf`, or even not implemented a= t all, only prefix `F`and its transformation is important.

More I th= ink about this more it look as great addition to language:
std::string a;
int b = =3D 0;
int c =3D 42;
db.run(F"select name as {a}, age as {b} from table wh= ere id =3D {c}"_sql);
=
auto i =3D 1;
auto j =3D <= /span>3;
FR"(
set x =3D {i};
set= b =3D {j};
set {i} =3D 3 * x + b + b;
)"_script;
assert(i =3D=3D = 9);

F"Log %f{3.5f} %3f{100f}= %d{5}"_printf;= // equal to printf(= "Log %f %3f %d", 3.5f, 100f, 5)




--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
To post to this group, send email to std-proposals@isocpp.org.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/4bce681e-e729-4124-9322-69291fdb6678= %40isocpp.org.
------=_Part_2335_1613922253.1518214346872-- ------=_Part_2334_264573856.1518214346871-- .