220 41385 article Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Andrey Semashev Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Improving compile times for non-template dependent member functions. 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[37.110.31.10]) by smtp.googlemail.com with ESMTPSA id j12-v6sm573888ljh.66.2019.01.23.08.11.50 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 23 Jan 2019 08:11:50 -0800 (PST) In-Reply-To: <6a72db2a-932d-4f79-ab68-7c1424e93b9d@isocpp.org> Content-Language: ru X-Original-Sender: andrey.semashev@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=G0tioA29; spf=pass (google.com: domain of andrey.semashev@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=andrey.semashev@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE 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:41385 Archived-At: On 1/23/19 6:58 PM, p groarke wrote: > I'll take a wild guess this has already been asked, thought-of or=20 > written about, but lets ask anyways. I'm curious why one cannot write=20 > the implementation of non-template dependent member function in a=20 > compile unit, in the hopes of improving compile times. >=20 > For example : >=20 > .h >=20 > | > template > structtest { > intval()const; >=20 > private: > intval {42}; > =C2=A0 =C2=A0 T t; > }; > | >=20 >=20 > .cpp >=20 > | > // I do not depend on T, can implement in compile unit. > // Declaration semantics unimportant. > inttest::val()const{ > returnval; > } > | >=20 >=20 > I remember a cppcon talk from Ubisoft, where they bypass this issue by=20 > inheriting a base class with non-template dependent behavior implemented= =20 > in their compile unit. Template dependent behavior is implemented in the= =20 > header of the derived class. > Why not offer this compilation behavior out-of-the-box? I assume, the main reason is that because the method is not instantiated=20 until it is ODR-used (e.g. called). This is a useful property, which, in=20 fact, may improve compile times if the method body causes a lot of other=20 template instantiations or expensive code generation. --=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. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/a97e361c-772e-6fb5-5ca8-d72250f45541%40gmail.com= .. .