220 33518 article Path: news.gmane.org!.POSTED!not-for-mail From: costelnistor12@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: A more advanced switch Date: Tue, 1 Aug 2017 14:24:04 -0700 (PDT) Lines: 266 Approved: news@gmane.org Message-ID: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_5435_1704948266.1501622644132" X-Trace: blaine.gmane.org 1501622649 23575 195.159.176.226 (1 Aug 2017 21:24:09 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 1 Aug 2017 21:24:09 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCGIBI4KUYIRB5HCQPGAKGQERCOTH2I@isocpp.org Tue Aug 01 23:24:04 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk0-f197.google.com ([209.85.220.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dcee0-0005dt-Ma for gclcip-std-proposals@m.gmane.org; Tue, 01 Aug 2017 23:24:00 +0200 Original-Received: by mail-qk0-f197.google.com with SMTP id i143sf13365004qke.14 for ; Tue, 01 Aug 2017 14:24:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=Mc3Tg+ZYkF9kq3DW+98U+hJzF5pATcCUYvGNvBxDOrk=; b=m4pgXGUGJfCttGzW29OlkKbJ0Q6zuVSxtDDG8SiXpbv+AR5aecbsgdPpunlrP7yw2A RTAk2NTgPq7TU9S0gvWCDPk/VXRpccTDtTos+cOZSTshP3W8dHyCEfD1OvJsEpTZLFna 9BDkeshOoNw+QcokbFEscJRFrvbIldjHO8cLIiKYiamrjbU3ZdaPeb1NbBLA7s/FF5PW gpnu4GBfdk2LfGyDyiV8azL49M62RLXjA0SgJntNtwxv3i2Fx84Lggi/MV5bwa5M4iJr +/s5/f7Y0b/2E5HVdGTPxSYIU2cTzol9h5d111fH8JYFGSOXJLZI5DqfyVe0LKBX9jFB Ox9Q== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=Mc3Tg+ZYkF9kq3DW+98U+hJzF5pATcCUYvGNvBxDOrk=; b=PSbwMKPqfNIvNme7/O8T6O2OcyU3Kh3gjf0i0ARrr+aE0TH6Tt+eF6aRDIzM7t3dge disSw7bTy2vyjF7cTVKX0HYDciC+pXII4J1ycjbIIAY6pDdtqSn2AaYi6G1H+wyvqCaF 4Gw9S02yFTEU8DKnHS3ArJPFrLCeAfIvWJhlmiwxG8sKHJUytQy9Ka8oRvy12qK14m5j d8SJ4lxUuI5BLEQoZ7+s1HJjmYkhZ7OwW1FoyVLbTmfg9dg/7QO5nbvz5/ClfS2I07ce +NAG50MeFeBpnlbXU9Eo4PflrBY7f1zbTXzcovihYXMjLqT6yZpVmq4Dl0Y/KGfi3gXn AzeQ== 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: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=Mc3Tg+ZYkF9kq3DW+98U+hJzF5pATcCUYvGNvBxDOrk=; b=MMvEZaI/vmmCNXq/AxyFKnwKvX8zrW0M6Lx73jSCBh88DXAiAVi6DrYLd4VTVRNKm4 CRzOED0ONWa9e1EcLae7xtk1ODRxzVVXSOlKnnXJ9btl/SQiQGioO+Oo9MDKDkij/N/Y hSDEQ5XL7vyft1wVxU36cOJsMJxgr/yc7+Z6VHWKHE5VhFu8fGuFekVPihLtLt+1DMsx Ri08hJ2ztmE5mw3mjUblPb4jloH0c9lo7qQCHR5BdHVcHx94xD6jC+pshgMm3sYFyi1v 4ycaegyAnbxogVEh6su1qLj5C8Goehuj8FWCGFPr5drTWYMjIgLS396aNP2VKW0Fiaga sEOQ== X-Gm-Message-State: AIVw110TDPfX5Fdnsticwp2lkPuO9jpBiCmBPpB7bSXTkli6m011Ulqz l5EdlRo3Fl+n1rWV X-Received: by 10.237.57.229 with SMTP id m92mr14749533qte.29.1501622646189; Tue, 01 Aug 2017 14:24:06 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.36.71.85 with SMTP id t82ls1072576itb.1.gmail; Tue, 01 Aug 2017 14:24:04 -0700 (PDT) X-Received: by 10.31.191.67 with SMTP id p64mr33380vkf.4.1501622644668; Tue, 01 Aug 2017 14:24:04 -0700 (PDT) X-Original-Sender: costelnistor12@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: 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:33518 Archived-At: ------=_Part_5435_1704948266.1501622644132 Content-Type: multipart/alternative; boundary="----=_Part_5436_466158694.1501622644133" ------=_Part_5436_466158694.1501622644133 Content-Type: text/plain; charset="UTF-8" Hello, I'm sorry if you talked about this here before, but I didn't watch this group and I couldn't find this thing when searching. I'm coming from another language named Pawn, it looks like C ~80%, but it has more advantages than C. Here's the official page: https://www.compuphase.com/pawn/pawn.htm . A problem in C++: "switch" is exactly like in C, I think it deserves an upgrade, as it can be used a lot, providing more speed and easier syntax than lots of "if" ... "else if" ... "else" lines. I know that simply updating it would break compatibility, so it may require another name instead of switch, or you can find any other backwards compatible alternative. I bet you can do this perfectly. For cases 0, 1, 2, 3, 4 and 5, 6 and "default" in C++ we have to do it like switch( variable ) { case 0: case 1: case 2: case 3: case 4: { // ... break; } case 5: case 6: { // ... break; } default: { // ... } } We have to use "case" for every, well, case when specifying a sequence, because it uses fallthrough. We have to use "break" to avoid that. I find this bad. Because of the necessity of using "break" we can't just "break" out of a loop if the switch is inside a loop. Also, if there are consecutive cases we have to specify each one of them. Additionally, we could also forget breaking. This "switch" isn't safe and is pretty old. In Pawn we can do it a lot better: switch( variable ) { case 0 .. 4: { // ... } case 5, 6: { // ... } default: { // ... } } 1. There's no need for break, there's no fallthrough. Advantage: we can easily "continue" and "break" loops from inside the "switch". 2. We can use ".." if using several cases that are consecutive in the same block of code, to specify an interval. I know that it's hard to have features accepted in such a popular standard, but upgrading switch is something that should really be considered ! C++17's [[fallthrough]] attribute is just as complicated as the "switch". It needs to be added everywhere or else we would get warnings (AFAIK). C++ needs a lot more syntactic sugar. Small and nice things are making the language more likeable. I think that you should watch other languages too for interesting small features. -- 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 email 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/f8c908e2-d06f-4cd1-bda0-fe2b97fd21f1%40isocpp.org. ------=_Part_5436_466158694.1501622644133 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hello, I'm sorry if you talked about this here before,= but I didn't watch this group and I couldn't find this thing when = searching.

I'm coming from another language named Pa= wn, it looks like C ~80%, but it has more advantages than C. Here's the= official page:=C2=A0https://www.compuphase.com/pawn/pawn.htm .
<= br>
A problem in C++: "switch" is exactly like in C, I = think it deserves an upgrade, as it can be used a lot, providing more speed= and easier syntax than lots of "if" ... "else if" ... = "else" lines. I know that simply updating it would break compatib= ility, so it may require another name instead of switch, or you can find an= y other backwards compatible alternative. I bet you can do this perfectly.<= div>
For cases 0, 1, 2, 3, 4 and 5, 6 and "default"= in C++ we have to do it like
switch( variable )
{
=C2=A0 = =C2=A0 cas= e <= span style=3D"color: #066;" class=3D"styled-by-prettify">0: case 1: case<= span style=3D"color: #000;" class=3D"styled-by-prettify"> 2: case 3: case 4:
=C2=A0 =C2=A0 {
=C2=A0 =C2=A0 =C2=A0 =C2=A0 // ...
=C2=A0 =C2=A0 =C2=A0 =C2=A0 break;
=C2=A0 =C2=A0 }

=C2=A0 =C2=A0 case 5: case 6:
=C2=A0 =C2= =A0 {
=C2=A0 =C2= =A0 =C2=A0 =C2=A0 // ...
=C2=A0 =C2=A0 =C2=A0 =C2=A0 break;
=C2=A0 =C2=A0 }

=C2=A0 =C2=A0 default:
=C2=A0 =C2=A0 {
=C2=A0 =C2=A0 =C2=A0 =C2=A0 // ...
=C2=A0 =C2=A0 }
}

We h= ave to use "case" for every, well, case when specifying a sequenc= e, because it uses fallthrough. We have to use "break" to avoid t= hat. I find this bad. Because of the necessity of using "break" w= e can't just "break" out of a loop if the switch is inside a = loop. Also, if there are consecutive cases we have to specify each one of t= hem. Additionally, we could also forget breaking. This "switch" i= sn't safe and is pretty old.

In Pawn we can do= it a lot better:
switch( variable )
{
=C2=A0 =C2=A0 case 0 .. 4:
=C2=A0 =C2=A0 {
=C2=A0 =C2=A0 =C2=A0 =C2=A0 // ...
=C2=A0 =C2=A0 }

=C2=A0 =C2=A0 case 5, 6:
=C2=A0 =C2=A0 {
=C2=A0 =C2=A0 =C2=A0 =C2=A0 // ...
=C2=A0 =C2=A0 }

=C2=A0 =C2=A0 default:
=C2=A0 =C2=A0 {
=C2=A0 =C2=A0 =C2=A0 =C2= =A0 // ...=
=C2=A0= =C2=A0 }<= /span>
= }

1. There's no need for break, there's no fallthrough. Advantage:= we can easily "continue" and "break" loops from inside= the "switch".
2. We can use ".." if using se= veral cases that are consecutive in the same block of code, to specify an i= nterval.

I know that it's hard to have feature= s accepted in such a popular standard, but upgrading switch is something th= at should really be considered ! C++17's [[fallthrough]] attribute is j= ust as complicated as the "switch". It needs to be added everywhe= re or else we would get warnings (AFAIK).

C++ need= s a lot more syntactic sugar. Small and nice things are making the language= more likeable. I think that you should watch other languages too for inter= esting small features.

--
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/f8c908e2-d06f-4cd1-bda0-fe2b97fd21f1= %40isocpp.org.
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