220 11503 article Path: news.gmane.org!not-for-mail From: walter1234 Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Controversy and debate: Uninitialized variables by default is a bug Date: Tue, 17 Jun 2014 18:27:14 -0700 (PDT) Lines: 92 Approved: news@gmane.org Message-ID: References: <60caa4ef-b32d-40fe-97b6-8918fbb2bd51@isocpp.org> <52d66b4b-a634-4e51-bdb5-5f6e188c01a8@isocpp.org> <3A9B04D2-9D20-4344-95FC-9BA1ED9E602B@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_1964_17289139.1403054834875" X-Trace: ger.gmane.org 1403054844 31812 80.91.229.3 (18 Jun 2014 01:27:24 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 18 Jun 2014 01:27:24 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDO7FOW36ILRB46VQOOQKGQEHXLCMDQ@isocpp.org Wed Jun 18 03:27:17 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ie0-f199.google.com ([209.85.223.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Wx4ei-0003sg-T6 for gclcip-std-proposals@m.gmane.org; Wed, 18 Jun 2014 03:27:17 +0200 Original-Received: by mail-ie0-f199.google.com with SMTP id rd18sf1389760iec.6 for ; Tue, 17 Jun 2014 18:27:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; 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 :content-type; bh=68ZyzQTXGVu3YNZuHuYD8eZWcPQFuHIzd6IjNReM8u8=; b=ExWXAzjLvJiZVJ6XoDQCTnDzNjP+Mlu50jCmqE4sqK0uPOLs6WN5PXhzf7Lk3+/9ta kmVl7cF2fp+fc0AbFi7poTZoRcpsdwNgG9kXpHyPLLjkMudJuuTkmVQQSKfSEph6xUMD jaAHmktcDwBdQxUuUq5eUp6jRwAXWLPdxERhguzFXFQzG3is4JZvxRtORS2aChyObu36 QApuGYh5Lo2r0EmcsPRdW+C6rv1E9GUthYGQBUk9uaThYM1UlqiUhDgcdcP1hEl8JtdC YMD0fDjA2K5MOJuI23crQXpmTy6aZvk3m83jOmwXhdAXD9IooICVH5akKT+bemFAD0bx 6IpQ== 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: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:content-type; bh=68ZyzQTXGVu3YNZuHuYD8eZWcPQFuHIzd6IjNReM8u8=; b=KiYEdncdcd/+/95mu3PmyYKWO7kcNCBNvuhlGmBfsmrt4PaYBesmJO5HU2Szqh/QZC 8HyYW8HqtdWXlFxj7LEnPquUqTcfyT7lLvhkhzyloxw5aa/L2yOppohYcZsnObzZTpXN fcKNkb++1YlWQfdiFY3ctuT8LpWZX3pXaIQEPGtuLvXYM/GoiUxjuXkAUQ8JA9uq2Clb dZDrZj9zSz57E9c0HwsStAOHvJIsvQk/6YyzZZn6QKLVhkauCFjvBqdd7Wu0BszsrauA x4rys93bvQYNnH6ekimmGcKwdOMhOe4rkq+xBGlSQEdaCrfIc+OmUAHlS0pseazmtyM3 o1TQ== X-Gm-Message-State: ALoCoQnHk/9tjNKe59/HQvifIh2BV9rwMAG2ka9cGBG4WLx05sTYqbZYfBXHm7+YpfaNj3Y9hNiN X-Received: by 10.182.213.106 with SMTP id nr10mr231115obc.30.1403054835987; Tue, 17 Jun 2014 18:27:15 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.98.225 with SMTP id o88ls4877214qge.88.gmail; Tue, 17 Jun 2014 18:27:15 -0700 (PDT) X-Received: by 10.140.95.176 with SMTP id i45mr7579qge.10.1403054835396; Tue, 17 Jun 2014 18:27:15 -0700 (PDT) In-Reply-To: <3A9B04D2-9D20-4344-95FC-9BA1ED9E602B@gmail.com> X-Original-Sender: walter2bz@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:11503 Archived-At: ------=_Part_1964_17289139.1403054834875 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable > I=E2=80=99ve not more than glanced at Rust, and don=E2=80=99t plan to, so= perhaps you=20 > could elaborate. Treating statements as expressions is common to many=20 > languages, but I don=E2=80=99t see the relevance. Do you mean, rather tha= n an=20 > if-else statement, the language prefers something more like the ternary= =20 > operator (perhaps with tuple un/packing), such that it tends to keep=20 > account of the assignments and you won=E2=80=99t forget one? > > [1] you can create scope blocks with temporaries, calculate something , and= =20 return it to assign to something in the outer scope; [2] Rust "match" (switch on steroids) has a return value, this is extremely= =20 versatile , given everything else match can do (destructuring and=20 additional 'if' guards on individual match arms) .=20 This of course removes the case where you assign to something within switch= =20 arms. [3] rust's if-else replaces the C++ ternary operator maybe I'm imagining it, but after using Rust i'm left with the perception= =20 that these features help you to avoid needing uninitialised variables. One thing rust doesn't do is have a return value for loops, but I would=20 really like them to add that (and copy python's for...else idea).. the=20 language is still in flux, so its not too late for them. --=20 ---=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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. ------=_Part_1964_17289139.1403054834875 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

I=E2=80=99ve not more than glanced at Rust, and = don=E2=80=99t plan to, so perhaps you could elaborate. Treating statements = as expressions is common to many languages, but I don=E2=80=99t see the rel= evance. Do you mean, rather than an if-else statement, the language prefers= something more like  the ternary operator (perhaps with tuple un/pack= ing), such that it tends to keep account of the assignments and you won=E2= =80=99t forget one?


[1= ] you can create scope blocks with temporaries, calculate something , and r= eturn it to assign to something in the outer scope;
[2] Rust "mat= ch" (switch on steroids) has a return value, this is extremely versatile , = given everything else match can do (destructuring and additional 'if' guard= s on individual match arms) . 
This of course removes the ca= se where you assign to something within switch arms.
[3] rust's i= f-else replaces the C++ ternary operator

maybe I'm= imagining it, but after using Rust i'm left with the perception that these= features help you to avoid needing uninitialised variables.

=
One thing rust doesn't do is have a return value for loops, but = I would really like them to add that (and copy python's for...else idea).. = the language is still in flux, so its not too late for them.

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