220 15330 <1a6e8394-b2f7-4c1a-b3cd-650b7968406f@isocpp.org> article Path: news.gmane.org!not-for-mail From: Leo Heinsaar Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Isn't it time we had the bool std::[container]::contains() family of methods? Date: Fri, 26 Dec 2014 10:18:49 -0800 (PST) Lines: 106 Approved: news@gmane.org Message-ID: <1a6e8394-b2f7-4c1a-b3cd-650b7968406f@isocpp.org> References: <0959f2f8-acdd-4786-b6f3-0f05c62dcee6@isocpp.org> <2df86492-548f-42c8-86d6-fe1c8ba3a5a9@isocpp.org> <2f390ec3-b259-4150-9771-cd0d02860348@isocpp.org> <3743ebda-3367-4fc3-922a-f38d98e57889@isocpp.org> <1bccb2dd-4aa4-4f07-8958-b1d6bf092630@isocpp.org> <46cc4da5-98d1-471f-ab31-714ac5502853@isocpp.org> <6ad78bb4-b21b-4978-90be-b99ef6d15414@isocpp.org> <1c016fbb-7268-4c69-b9ab-510fb78c4125@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_6335_2115259800.1419617930022" X-Trace: ger.gmane.org 1419617939 23734 80.91.229.3 (26 Dec 2014 18:18:59 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 26 Dec 2014 18:18:59 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCFYDAXXQYEBBCWN62SAKGQEXRS6YPY@isocpp.org Fri Dec 26 19:18:53 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pd0-f200.google.com ([209.85.192.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Y4ZTQ-0005bB-FE for gclcip-std-proposals@m.gmane.org; Fri, 26 Dec 2014 19:18:52 +0100 Original-Received: by mail-pd0-f200.google.com with SMTP id r10sf77243095pdi.3 for ; Fri, 26 Dec 2014 10:18:51 -0800 (PST) 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 :content-type:x-original-sender:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=QhVbXQSQ28Obz8QKhKzzOZvWgXC0IANKNfPEm/wlUWg=; b=au25zKmVvIv6pQmjshQwbPxo63+APicYpBkAwtXy8RpNzVQ4KEgkgMshslA/BylAx3 d40BhUb44eA6m3/jMJ1g/DdQoebwe8xONfQQ4q34Akx+g/yk/a8Olk5PRNC8VU4Dlw8c S1J3r+7XGNiXISz3l1KrEcM/wFHn2KylgqDMpfV1xHfhnEHisBcpzh6taqO8kiHz9e14 vqQjYz2CKX4a9bbZ46n8ax+x6AfX1WOLtiSkeCgVdYYAzKs0+MvTCU/kDfNjmfFMdD8X 7hCsIh/9JzCEkx645bCDe2cLIsLqALlHE2GI/WtLt03ZTtxUPbgijGZSE2DS5mkZe6qz Fm0g== 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:content-type:x-original-sender:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=QhVbXQSQ28Obz8QKhKzzOZvWgXC0IANKNfPEm/wlUWg=; b=WRwffpsVAeBjkkCXp3x9ybUnifovQKJ8JCYaaNM810eyZ/wDNjxXuE6Hl4VlXPAhbq 6BTS+kmly2xEvgrPyKKsUblcvOnnp1KJQlPkPR8nEQVomqxz3kOQp5jofMrvxD2404mh 9G+jLhzsE83HfJq0GeO0Q9oslhHsrSbQ5hrSABtQif9953vAps/gf1lCxhBvgx6mJY1e kfXfQ+yfmMuY8Ua+JTArxDk53ty1cUSXnIYGMZLNPfzgY1mNZZURdKjnRKfmqFCL42Wg JyexQNugtxg8UbOAjKx5lqhaz1sU+Lg9ur+nPsdOUS4mmE7cIA23o9Mk5KEVjh9KaqK4 ppPg== X-Gm-Message-State: ALoCoQk4tqyLx+010P/1Pjz3pfNBPmKyJL6/i84R+xaDEp+FhbSV46/33YPX5fQF7FLRpubLj9Z9 X-Received: by 10.66.248.10 with SMTP id yi10mr31651841pac.0.1419617931193; Fri, 26 Dec 2014 10:18:51 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.97.73 with SMTP id l67ls1594549qge.69.gmail; Fri, 26 Dec 2014 10:18:50 -0800 (PST) X-Received: by 10.140.102.211 with SMTP id w77mr11791qge.28.1419617930365; Fri, 26 Dec 2014 10:18:50 -0800 (PST) In-Reply-To: <1c016fbb-7268-4c69-b9ab-510fb78c4125@isocpp.org> X-Original-Sender: leoheinsaar@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:15330 Archived-At: ------=_Part_6335_2115259800.1419617930022 Content-Type: multipart/alternative; boundary="----=_Part_6336_1727166162.1419617930022" ------=_Part_6336_1727166162.1419617930022 Content-Type: text/plain; charset=UTF-8 On Friday, December 26, 2014 10:02:07 PM UTC+4, Andy Prowl wrote: > > While I agree with most of what has been written in the last few messages, > I feel we are slowly diverging from the purpose of the original post, > perhaps unnecessarily enlarging its scope. > Yep guys, felt the same divergence. > I think an algorithm like "contains()" for "containers" is such an obvious > and elementary operation that it ought to be in the standard library: it is > simpler, easier to teach, and easier to understand than the current "!= > end()" idiom. > > Exactly the point: a simple, easy-to-read, very-frequently-used, bool-returning contains(). If we want to recover an iterator, we just use find(), don't we? (And in cases like that the code usually isn't concerned about the existence of an element in a container, but wants to do something.) > IMO a proposal should be written for adding this function, and keeping its > scope narrow may increase its chances to get accepted. > > Perhaps it would be a good idea to at this point simply raise the awareness of the need for contains() and wait for concepts, without which, as Bjarne has also pointed out many times, it is hard to get all container algorithms perfect. The proposed ranges are also likely to affect. > Kind regards, > > Andy > -- --- 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. 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On Friday, December 26, 2014 10:02:07 PM UTC+4, Andy P= rowl wrote:
Wh= ile I agree with most of what has been written in the last few messages, I = feel we are slowly diverging from the purpose of the original post, perhaps= unnecessarily enlarging its scope.

Yep guys, felt the same divergence.
 
I think an algorithm li= ke "contains()" for "containers" is such an obvious and elementary operatio= n that it ought to be in the standard library: it is simpler, easier to tea= ch, and easier to understand than the current "!=3D end()" idiom.

 
Exactly the point: a simple, easy-to= -read, very-frequently-used, bool-returning contains(). If we want to recov= er an iterator, we just use find(), don't we? (And in cases like that the c= ode usually isn't concerned about the existence of an element in a containe= r, but wants to do something.)
 
IMO a proposal should be written fo= r adding this function, and keeping its scope narrow may increase its chanc= es to get accepted.


Perhaps it would be a good idea to at this point simply raise the awarene= ss of the need for contains() and wait for concepts, without which, as Bjar= ne has also pointed out many times, it is hard to get all container algorit= hms perfect. The proposed ranges are also likely to affect.
 = ;
K= ind regards,

Andy

--

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