220 29685 article Path: news.gmane.org!.POSTED!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: compiler should infer last semicolon of culy brace block... it makes lambas look better.... Date: Tue, 6 Dec 2016 13:30:54 -0800 (PST) Lines: 167 Approved: news@gmane.org Message-ID: References: <99df401b-562e-424f-9c17-01575f8b47e1@isocpp.org> <7ac0450f-1fe9-4787-bfba-5bde4c08abb8@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_92_1533801044.1481059855091" X-Trace: blaine.gmane.org 1481059859 27543 195.159.176.226 (6 Dec 2016 21:30:59 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 6 Dec 2016 21:30:59 +0000 (UTC) Cc: wm2015email@gmail.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCEKFTV6ZUMBBD64TTBAKGQEZJHN3EA@isocpp.org Tue Dec 06 22:30:54 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-io0-f197.google.com ([209.85.223.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cENK9-0006O9-5n for gclcip-std-proposals@m.gmane.org; Tue, 06 Dec 2016 22:30:53 +0100 Original-Received: by mail-io0-f197.google.com with SMTP id m203sf263067357iom.6 for ; Tue, 06 Dec 2016 13:30:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc: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=lDEqArvyCFHiT1e2vIgMXafYpuDmbAnIy6rUS4UMLdk=; b=Rekydz3AIm5k5AMAFCeQOynL8Loc2YB2hoMNs9zlPamcj7ioYYL8W5Lp65CXaMiwa3 eG6Vi2hiNbGuuCnwioJbc9014niIJrxE2rl/fuBplZxH6Xj6lwpY+9bFpG7cTw0lXP8j fLasONg4BN0Y/uxVlYIjseH/85CIeZrINVLXebxJ7q3+6nVmya3/49lU324eCibRhGgl jgvvcDq+FiAhR8VHYyxsD6S7ElIVZsxfgMZyRZPW+sxPHK0jtE9oPZ1DsEYb2EuE9raB vBHjeq0R+R/jXBR6PHMIg5PL7fB70EWHBCNjU5SxM1E65Tbjs8gQv5GKLPcZF04DJOFl S/Zw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc: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=lDEqArvyCFHiT1e2vIgMXafYpuDmbAnIy6rUS4UMLdk=; b=rx/K/RAbAvc7hKGT/nNiVTwahjlV8u7aFfD3wJSHhl4Ng7r9IRwr5pW7RJaNpAr87Q a6mW6K5mduNntrhbwHTidj8/ZA3Z2qKNC1mveG9K2xNH5OlBpu5qBF0sfnDm9WDze6BX v3BAVsgBC4eMWoYwNL4kilVYZtI+TSH4LZg3ZEjFSffwjJsD8BxpOJaMk8vjsIJHztP/ 1YP/q5BFCRzN1ly/6yu0E2ZQ8ALd3Au2kAmiP2pQ6/lGVFAN3YGjuEgVd7MKPpZwh2iO NPvqYW1PMqX0zrJsTWWQDsOXlyehTbgH8enaGteYjpFQgzEFb9nNkaY8huO6KXZV4Jk2 SNZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc: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=lDEqArvyCFHiT1e2vIgMXafYpuDmbAnIy6rUS4UMLdk=; b=IkkusES0J2H8KVxLfmmV2UMU60W9xeVBYinOfzwDnXyn65COW9vvtoU+rQKbR5c2ea QakGk8AVEFlSHkibnmj0L56DFefa0O3Rhxiypl+urxR/nW2uBQOIB2whW1exd9DWlOHY KmYeweLCtYG1VynAzh5CEtDWU/bDQM3vjtwL86Yw/1NFeIleiv0VbIYtLGj6gL1gsQIL ZAH6/suZwu4Fxhci8rIWmKF3t8uZmAVLnde/ZeRFbtM+3uUe86c69NYTtcHFI6N5jbWd FcHLEQ59gh/xR+l5AKLwx7XtNfpphIfzohgXo7E3F1IyBL48VXZ8sDyRXtSAeuT43n3Z 7fNg== X-Gm-Message-State: AKaTC00oOucgV/j5bYArHZTBUFv3be1czbZgwFV5fF26/+jqbN7GbFJ5lekYbKt7BNa37w== X-Received: by 10.107.178.65 with SMTP id b62mr14718829iof.64.1481059856595; Tue, 06 Dec 2016 13:30:56 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.58.38 with SMTP id j35ls2423529otc.17.gmail; Tue, 06 Dec 2016 13:30:55 -0800 (PST) X-Received: by 10.157.8.134 with SMTP id 6mr4198782otf.17.1481059855697; Tue, 06 Dec 2016 13:30:55 -0800 (PST) In-Reply-To: <7ac0450f-1fe9-4787-bfba-5bde4c08abb8@isocpp.org> X-Original-Sender: jmckesson@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:29685 Archived-At: ------=_Part_92_1533801044.1481059855091 Content-Type: multipart/alternative; boundary="----=_Part_93_150103289.1481059855091" ------=_Part_93_150103289.1481059855091 Content-Type: text/plain; charset=UTF-8 On Monday, December 5, 2016 at 5:33:29 PM UTC-5, Erich Keane wrote: > > On Friday, December 2, 2016 at 6:49:08 AM UTC-8, wm201...@gmail.com wrote: >> >> Good code vs.Bad Code >> >> #define LAMBA [=] >> >> menu1.callback("Log->Clear", LAMBDA() {dosomething1(); dosomthing2()}); >> >> ^^^ Abouve with Inferred last semi-colon: LOOKS GOOD, but a compiler >> error. >> Why not make it legal to infer the last semicolon in a curly brace block? >> >> >> Compiles... but the syntax gets on your nerves: >> >> menu1.callback("Log->Clear", [=]() {dosomething1(); >> dosomthing2();}); //extra semicolon at the end >> >> >> sure Laugh now. But all those semicolons add up in a large program... >> >> >> Actually while we are on this one. I always like the "perl feature of >> allowing extra "commas" when defining a list. this feature sames a huge >> amount of lot of time when writing programs that write programs without all >> the extra garbage code needed to detect the end of list to remove comma at >> the end of the list: >> >> GOOD: (thank you perl) >> vector blah { >> "one", >> "two", >> "three", // <= extra comma ok... ignored without warn >> }; >> >> BAD: (no thanks c++: lighten up a little bit c++ compiler... ) >> vector blah { >> "one", >> "two", >> . "three" // <=== no comma allowed here... now all of my loops need >> extra if block to detect end of list when writing programs that write >> programs... >> }; >> >> now you are asking... why on earth would anybody ever want to write a >> program that writes a program? >> it happens more often than you think... >> >> >> >> This seems like a pretty minor thing, I'm not a huge fan of changing the > grammar that much in the name of saving single characters. Others have > mentioned the many problems with automatic return type. > > That said, 1 feature that I REALLY miss from C# is the single-line > lambdas (https://msdn.microsoft.com/en-us/library/bb397687.aspx). > > Essentially: > > auto func = (a, b, c) => a + b + c; > > Would be the same as: > > auto func = [](auto a, auto b, auto c) { return a + b + c;}; > Because C++ is more complex than C#, what it converts to should be more complex than that, involving `noexcept` and `decltype` deduction of the return expression (for SFINAE purposes). There's a more full discussion of this sort of thing here .. However, don't get your hopes up for typeless parameters. -- 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/db9eb530-1da1-47d2-98f5-a4c08ec43cd4%40isocpp.org. ------=_Part_93_150103289.1481059855091 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Monday, December 5, 2016 at 5:33:29 PM UTC-5, Erich Kea= ne wrote:
On F= riday, December 2, 2016 at 6:49:08 AM UTC-8, wm201...@gmail.com wrot= e:
Good code vs.Bad= Code

#define LAMBA [=3D]

menu1.callback("Log->Clear&= quot;, LAMBDA() {dosomething1(); dosomthing2()});

^^^ Abouve with In= ferred last semi-colon: LOOKS GOOD, but a compiler error.=C2=A0
Why not= make=20 it legal to infer the last semicolon in a curly brace block?


Co= mpiles... but the syntax gets on your nerves:

=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0 menu1.callback("Log->Clear", [=3D]() {do= something1(); dosomthing2();}); //extra semicolon at the end


sur= e Laugh now.=C2=A0 But all those semicolons add up in a large program...

Actually while we are on this one.=C2=A0 I always like the "p= erl feature of allowing extra "commas" when defining a list.=C2= =A0 this feature sames a huge amount of lot of time when writing programs t= hat write programs without all the extra garbage code needed to detect the = end of list to remove comma at the end of the list:

GOOD:=C2=A0 (tha= nk you perl)
=C2=A0 vector<string> blah {
=C2=A0=C2=A0=C2=A0 &q= uot;one",
=C2=A0=C2=A0=C2=A0 "two",
=C2=A0=C2=A0=C2=A0= "three",=C2=A0 // <=3D extra comma ok... ignored without warn=
=C2=A0 };

BAD: (no thanks c++: lighten up a little bit c++ compi= ler... )
=C2=A0 vector<string> blah {
=C2=A0=C2=A0=C2=A0 "= one",
=C2=A0=C2=A0=C2=A0 "two",
. =C2=A0=C2=A0 "t= hree"=C2=A0 // <=3D=3D=3D no comma allowed here... now all of my lo= ops need extra if block to detect end of list when writing programs that wr= ite programs...
=C2=A0 };

now you are asking... why on earth woul= d anybody ever want to write a program that writes a program?
it happens= more often than you think...



This s= eems like a pretty minor thing, I'm not a huge fan of changing the gram= mar that much in the name of saving single characters.=C2=A0 Others have me= ntioned the many problems with automatic return type.

That said, 1 f= eature that I REALLY miss from C# is=C2=A0 the single-line lambdas (https://msdn.microsoft.com/en-us/library/bb397687.aspx).
Essentially:

auto func =3D (a, b, c) =3D> a + b + c;

Wou= ld be the same as:

auto func =3D [](auto a, auto b, auto c) { return= a + b + c;};

Because C++ is more comp= lex than C#, what it converts to should be more complex than that, involvin= g `noexcept` and `decltype` deduction of the return expression (for SFINAE = purposes). There's a more full discussion of this = sort of thing here.

However, don't get your hopes up for typ= eless parameters.

--
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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/db9eb530-1da1-47d2-98f5-a4c08ec43cd4= %40isocpp.org.
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