220 29645 article Path: news.gmane.org!.POSTED!not-for-mail From: Mikhail Semenov Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: compiler should infer last semicolon of culy brace block... it makes lambas look better.... 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[2607:f8b0:400d:c0d::22d]) by mx.google.com with ESMTPS id h24si6802542qtf.266.2016.12.04.02.44.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 04 Dec 2016 02:44:23 -0800 (PST) Received-SPF: pass (google.com: domain of mikhailsemenov1957@gmail.com designates 2607:f8b0:400d:c0d::22d as permitted sender) client-ip=2607:f8b0:400d:c0d::22d; Original-Received: by mail-qt0-x22d.google.com with SMTP id n6so290768338qtd.1 for ; Sun, 04 Dec 2016 02:44:23 -0800 (PST) X-Received: by 10.200.37.241 with SMTP id f46mr45181635qtf.164.1480848263194; Sun, 04 Dec 2016 02:44:23 -0800 (PST) Original-Received: by 10.140.83.75 with HTTP; Sun, 4 Dec 2016 02:44:22 -0800 (PST) In-Reply-To: <1480711391.2485.1.camel@gmail.com> X-Original-Sender: mikhailsemenov1957@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of mikhailsemenov1957@gmail.com designates 2607:f8b0:400d:c0d::22d as permitted sender) smtp.mailfrom=mikhailsemenov1957@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=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:29645 Archived-At: --001a11410152b1c0c80542d2dad7 Content-Type: text/plain; charset=UTF-8 The C/C++ rules on semicolons in statements (not declarations) are a bit odd in contrast to other languages like Pascal, where semicolons are required only between statements in a compound statement (I am using C syntax to show this): {S1;S2;...;Sn} But, it also mean that a semicolon is not used before "else" (we could look into this as well, whether it is viable option): if (a>b) then x=a else x = b But, in C/C++, there is the ugly switch statement, where semicolons are probably required as well. In addition, in some languages, the value {S1;S2;...;Sn} is the value of Sn if it is the last executed statement/expression; otherwise it is the value of the expression in the return statement. All this can probably be implemented in C++, but all the syntactic ambiguities should be carefully examined. An then we will be able to write [&y](int x) { y += x; x } On 2 December 2016 at 20:43, Daniel Boles wrote: > For sure, that seems to be an irresolvable ambiguity that makes > 'implied return' a non-starter. > > The optional semicolon is cute, I guess, but hardly the main issue with > expressions of the complexity cited here. > > -- > 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/1480711391.2485.1.camel%40gmail.com. > -- 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/CAMeU-s36yo6iSW7kn%2BD9ZGAZzcgUEg9MQ6O0vfc9U-JjjzQi6A%40mail.gmail.com. --001a11410152b1c0c80542d2dad7 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
The C/C++ rules on semicolons in statements (not decl= arations) are a bit odd in contrast to other languages like Pascal, where= =C2=A0 semicolons are required only between statements in a compound statem= ent (I am using C syntax to show this):
{S1;S2;...;Sn}
=
But, it also mean that a semicolon is not used before "= else" (we could look into this as well, whether it is viable option):<= /div>
if (a>b) then x=3Da else x =3D b

But,= in C/C++, there is the=C2=A0ugly switch statement, where semicolons are pr= obably required as well.


In additio= n, in some languages, the value {S1;S2;...;Sn} is the value of Sn if it is = the last executed statement/expression; otherwise it is the value of the ex= pression in the return statement.

All this can pro= bably be implemented in C++, but all the syntactic ambiguities should be ca= refully examined.

An then we will be able to write=
[&y](int x) { y +=3D x; x }





On 2 December 2016 at 20:43, Daniel Boles <db0451@g= mail.com> wrote:
For sure= , that seems to be an irresolvable ambiguity that makes
'implied return' a non-starter.

The optional semicolon is cute, I guess, but hardly the main issue with
expressions of the complexity cited here.

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