220 33148 article Path: news.gmane.org!.POSTED!not-for-mail From: Brittany Friedman Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: template class to do default integral types initalization Date: Fri, 7 Jul 2017 14:42:53 -0500 Lines: 169 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="94eb2c06001a770cb40553bf705c" X-Trace: blaine.gmane.org 1499456581 10891 195.159.176.226 (7 Jul 2017 19:43:01 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 7 Jul 2017 19:43:01 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCHLPXGUXMJBBP6I77FAKGQEOMQJVIA@isocpp.org Fri Jul 07 21:42:56 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f200.google.com ([209.85.161.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dTZ9P-0002Jo-93 for gclcip-std-proposals@m.gmane.org; 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[2607:f8b0:400d:c09::230]) by mx.google.com with ESMTPS id 35si4140825qtt.80.2017.07.07.12.42.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Jul 2017 12:42:54 -0700 (PDT) Received-SPF: pass (google.com: domain of fourthgeek@gmail.com designates 2607:f8b0:400d:c09::230 as permitted sender) client-ip=2607:f8b0:400d:c09::230; Original-Received: by mail-qk0-x230.google.com with SMTP id 16so35850137qkg.2 for ; Fri, 07 Jul 2017 12:42:54 -0700 (PDT) X-Received: by 10.55.158.19 with SMTP id h19mr64397078qke.201.1499456574260; Fri, 07 Jul 2017 12:42:54 -0700 (PDT) Original-Received: by 10.140.20.202 with HTTP; Fri, 7 Jul 2017 12:42:53 -0700 (PDT) In-Reply-To: X-Original-Sender: fourthgeek@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.b=YHnWs4UL; spf=pass (google.com: domain of fourthgeek@gmail.com designates 2607:f8b0:400d:c09::230 as permitted sender) smtp.mailfrom=fourthgeek@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:33148 Archived-At: --94eb2c06001a770cb40553bf705c Content-Type: text/plain; charset="UTF-8" On Fri, Jul 7, 2017 at 2:09 PM, ar wrote: > 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_; > }; > It seems to me that int valA_=0 is easier to type and understand than extype valA_ . Do you disagree? It looks like you can use -Weffc++ in clang/gcc to find uninitialized members. Together this would address your concerns i think. -- 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/CADbh%2BeSiSzAXC9UFrL6mWEVjLJdG%3Dd7N03O0FV_iA0nv8i21YA%40mail.gmail.com. --94eb2c06001a770cb40553bf705c Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Fri, Jul 7, 2017 at 2:09 PM, ar <ar123456@gmail.com>= wrote:
Hi

I am an application developer in the telcom industry 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_;=
};

It seems to me that =C2=A0 =C2=A0in= t valA_=3D0 =C2=A0 =C2=A0is easier to type and understand than =C2=A0 =C2= =A0extype<int> valA_ =C2=A0 . Do you disagree?

It = looks like you can use -Weffc++ =C2=A0in clang/gcc to find uninitialized me= mbers. Together this would address your concerns i think.

--
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