220 12595 <038222e0-66c3-4837-b158-e911dffb3c55@isocpp.org> article Path: news.gmane.org!not-for-mail From: Adi Shavit Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Questions about N3949 - Scoped Resource - Generic RAII Wrapper for the Standard Library Date: Sun, 31 Aug 2014 07:03:18 -0700 (PDT) Lines: 69 Approved: news@gmane.org Message-ID: <038222e0-66c3-4837-b158-e911dffb3c55@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_146_320931048.1409493798857" X-Trace: ger.gmane.org 1409493807 11096 80.91.229.3 (31 Aug 2014 14:03:27 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 31 Aug 2014 14:03:27 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDMLX45JSIJBBJ6WRSQAKGQEIZCCS6A@isocpp.org Sun Aug 31 16:03:21 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f200.google.com ([209.85.213.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XO5iy-0002kC-St for gclcip-std-proposals@m.gmane.org; Sun, 31 Aug 2014 16:03:21 +0200 Original-Received: by mail-ig0-f200.google.com with SMTP id uq10sf25174886igb.3 for ; Sun, 31 Aug 2014 07:03:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; 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:content-type; bh=RHEEyNzn8WwmsDIl+nlegJyyfm6fICLL1HtWGHnm8ro=; b=MTSnQqOKPek/vwW6ypY6e8HPRXVT4nCuw37r+uGGK+gReuywL4FLmu5FTeObWJcqje 2CuWbZsi12XoFyxcvK5eHuW3lhY7Z5TYVSULLz64twY2IAcWsPar70o8Kv+awZGKMWZw Gm5mUfZHJVlP5StvbKqexNiuNL8WZ6srrGniTU2RJC3sJI4XgrPhEPjmjKYZqs3tv/iu Df48d5U7mPPIV4tQLZotq0QTtzDNuiejX+h+r+lMrqplkdim13o9YppUFfDt5cYhSu6j kTYyW04dslSfRGu+uIITsMJw4miHX6vNeh2m1gS1wU7kzHmBOx4TfncQaYg2j94dASjh reUg== 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: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=RHEEyNzn8WwmsDIl+nlegJyyfm6fICLL1HtWGHnm8ro=; b=Dw20FCwp7vOO6TTbBQYvcc8GRqDm76F7mnE/LeNrwz2azwbaNaEUpdMJi1rMdl8eci XkegvYqow0guyImacNBCtRn6507JupWJnca61a54CKqPSHtkvMTCxug/phuSfLWze9Fj uNdoV+HcqT+vmgH8yGW0WLjfpHLZEU6NxZ8GawTVl35DLYPOcZOv02WdKHOXl9F9D3aK GRchu4C1FG2VL5dZejj4Ihxo0w+HDiVsba7pTzDwX6fRagCEc0pjLf6o/fnJ/vatHNDz z5cgdWw/pZam18TWK86Dfba6eknKT5yA0AeKhV/Ouj4ddug/MWGI+RX94qAMJVlX/f8B EKGw== X-Gm-Message-State: ALoCoQkgExy6DfGiYfpZV8y4+F0nSB3bmx5tlu61Oas6bLuNGLe+KKBslk6pOXhhZcRPQyW91VEc X-Received: by 10.182.186.4 with SMTP id fg4mr13146373obc.9.1409493799789; Sun, 31 Aug 2014 07:03:19 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.84.176 with SMTP id l45ls1678878qgd.81.gmail; Sun, 31 Aug 2014 07:03:19 -0700 (PDT) X-Received: by 10.140.105.52 with SMTP id b49mr455319qgf.3.1409493799062; Sun, 31 Aug 2014 07:03:19 -0700 (PDT) X-Original-Sender: adishavit@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:12595 Archived-At: ------=_Part_146_320931048.1409493798857 Content-Type: text/plain; charset=UTF-8 Hi, It is often useful to have resources as members of a class to be cleaned upon destruction (this is what RAII is all about!). However, to declare a member of scoped_resource in the class header, I would need to know the type of the deleter (as opposed to, e.g. shared_ptr which does not require this). I guess I could use decltype in the member type definition, but that would require stating the actual deleter at 2 different places: header + the initialization. All the examples I saw use 'auto' for local scope, but AFAIK, you cannot use auto in the class declaration since the size needs to be known at compile time. Am I missing something here or is this by design? What is the rational for this and how would one a succinct scoped_resource declaration? Warm regards, Adi -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. ------=_Part_146_320931048.1409493798857 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Hi,

  It is often useful to have r= esources as members of a class to be cleaned upon destruction (this is what= RAII is all about!).
However, to declare a member of scoped_reso= urce in the class header, I would need to know the type of the deleter (as = opposed to, e.g. shared_ptr which does not require this).
I guess= I could use decltype in the member type definition, but that would require= stating the actual deleter at 2 different places: header + the initializat= ion.

All the examples I saw use 'auto' for local s= cope, but AFAIK, you cannot use auto in the class declaration since the siz= e needs to be known at compile time.
Am I missing something here = or is this by design?
What is the rational for this and how would= one a succinct scoped_resource declaration?

Warm = regards,
Adi
 

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