220 33147 article Path: news.gmane.org!.POSTED!not-for-mail From: ar Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: template class to do default integral types initalization Date: Fri, 7 Jul 2017 15:09:28 -0400 Lines: 150 Approved: news@gmane.org Message-ID: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="001a1145b8deec121d0553bef876" X-Trace: blaine.gmane.org 1499454570 29920 195.159.176.226 (7 Jul 2017 19:09:30 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 7 Jul 2017 19:09:30 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDHJNJE2R4MRB2NY77FAKGQEDAVHIFA@isocpp.org Fri Jul 07 21:09:26 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yb0-f199.google.com ([209.85.213.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dTYd3-0007V2-MX for gclcip-std-proposals@m.gmane.org; Fri, 07 Jul 2017 21:09:25 +0200 Original-Received: by mail-yb0-f199.google.com with SMTP id l5sf31431254ybb.6 for ; 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[2607:f8b0:400d:c09::235]) by mx.google.com with ESMTPS id v5si3904564qkl.123.2017.07.07.12.09.29 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Jul 2017 12:09:29 -0700 (PDT) Received-SPF: pass (google.com: domain of ar123456@gmail.com designates 2607:f8b0:400d:c09::235 as permitted sender) client-ip=2607:f8b0:400d:c09::235; Original-Received: by mail-qk0-x235.google.com with SMTP id v143so35143860qkb.0 for ; Fri, 07 Jul 2017 12:09:29 -0700 (PDT) X-Received: by 10.55.207.140 with SMTP id v12mr62731036qkl.49.1499454568664; Fri, 07 Jul 2017 12:09:28 -0700 (PDT) Original-Received: by 10.140.25.141 with HTTP; Fri, 7 Jul 2017 12:09:28 -0700 (PDT) X-Original-Sender: ar123456@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.b=gfqkkmpt; spf=pass (google.com: domain of ar123456@gmail.com designates 2607:f8b0:400d:c09::235 as permitted sender) smtp.mailfrom=ar123456@gmail.com; dmarc=pass (p=NONE sp=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:33147 Archived-At: --001a1145b8deec121d0553bef876 Content-Type: text/plain; charset="UTF-8" Hi I am an application developer in the telcom industry with 30+ years of experience with 15+ years of heavy c++ for high end networking devices. I am working with code bases that started well over 15 years ago and there is no end in sight, hence, writing maintainable code is of natural interest to me. One of the ideas in this area is to have all members to have default constructors. If encapsulating class is copyable/movable/assignable, members should have copy/move/assignment. Hence, adding new members would not require changes in constructors/assignments. Hence everybody have to write its own wrapper providing default constructor for integral types. I do believe that this approach has a lot of merit and it will be popular, hence, it makes sense to support it in standard library to avoid dealing with 10000 implementations of the same simple idea. The example is below. Thank you, Aleksey Romanov =============================================================== // Trivial wrapper class to add default initialization // to integral types. // // PROs: // It seems that it will be used often // It is 100% optional - does not affect existing of planned code // It is trivially small // It is used only in class definitions // It does not require casts // // CONs: // Yet another thing to track and document namespace std { template class extype { public: extype() : val_() {} extype(T const& t) : val_(t) {} extype(T&& t) : val_(move(t)) {} operator const T&() const { return val_; } operator T&() { return val_; } private: T val_; }; } // Usage example is below // // Note: // 1. The extype is used only inside class. // 2. Resolves code maintenance issue: if valC_ is added // there is no need to make chages in constructors class X { public: X() {} ... int valA() const { return valA_; } int valB() const { return valB_; } private: extype valA_; extype valB_; }; -- 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/CA%2BfXA1B3TD29whzpCcuMH3H63nbp8tOWn1f3E7HBEnC6piYFkA%40mail.gmail.com. --001a1145b8deec121d0553bef876 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi

I am an application developer in the telcom indu= stry with 30+ years of experience with 15+ years of heavy c++ for high end=20 networking devices.

I am working with code bases that started=20 well=C2=A0 over 15 years ago and there is no end in sight, hence, writing= =20 maintainable code is of natural interest to me.

One of the ideas in this area is to have all members to have default=20 constructors. If encapsulating class is copyable/movable/assignable,=20 members should have copy/move/assignment. Hence, adding new members would n= ot require changes in constructors/assignments.

Hence everybody have to write its own wrapper providing default constructor=20 for integral types. I do believe that this approach has a lot of merit=20 and it will be popular, hence, it makes sense to support it in standard=20 library to avoid dealing with 10000 implementations of the same simple=20 idea.

The example is below.

= Thank you,

Aleksey Romanov

=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D


// Trivial w= rapper class to add default initialization
// to integral types.
//// PROs:
//=C2=A0=C2=A0 It seems that it will be used often
//=C2= =A0=C2=A0 It is 100% optional - does not affect existing of planned code//=C2=A0=C2=A0 It is trivially small
//=C2=A0=C2=A0 It is us= ed only in class definitions
//=C2=A0=C2=A0 It does not requi= re casts
//
// CONs:
//=C2=A0=C2=A0 Yet another thing to tra= ck and document

namespace std {

template<typename T>class extype
{
public:
=C2=A0=C2=A0=C2=A0 extype() : val_() {}=C2=A0=C2=A0=C2=A0 extype(T const& t) : val_(t) {}
=C2=A0=C2=A0=C2= =A0 extype(T&& t) : val_(move(t)) {}
=C2=A0=C2=A0=C2=A0
=C2= =A0=C2=A0=C2=A0 operator const T&() const { return val_; }
=C2=A0=C2= =A0=C2=A0 operator T&() { return val_; }
private:
=C2=A0=C2=A0=C2= =A0 T val_;
};

}

// Usage example is below
//
// Not= e:
//=C2=A0=C2=A0 1. The extype is used only inside class.
//=C2=A0= =C2=A0 2. Resolves code maintenance issue: if valC_ is added
//=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0 there is no need to make chages in constructors
cl= ass X {
public:
=C2=A0=C2=A0=C2=A0 X() {}
=C2=A0=C2=A0=C2=A0 ...=C2=A0=C2=A0=C2=A0 int valA() const { return valA_; }
=C2=A0=C2=A0=C2= =A0 int valB() const { return valB_; }

private:
=C2=A0=C2=A0=C2= =A0 extype<int> valA_;
=C2=A0=C2=A0=C2=A0 extype<int> valB_;=
};

--
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