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October 09, 2012 why are c++ template instantiations inherently slow? | ||||
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In this post: http://article.gmane.org/gmane.comp.lib.boost.devel/189925 Eric indicates that Walter Bright believes, in c++: that instantiating a template is inherently expensive, and certain features of the C++ language (ADL, partial specialization, etc.) force that to be the case. Walter, if Eric is remembering correctly, could you provide a little more explanation on why this is so or provide a link to some document supporting this conclusion? TIA. -regards, Larry |
November 01, 2012 Re: why are c++ template instantiations inherently slow? | ||||
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Posted in reply to evansl | On Tue, 09 Oct 2012 15:59:26 -0500 evansl <cppljevans@suddenlink.net> wrote: > In this post: > > http://article.gmane.org/gmane.comp.lib.boost.devel/189925 > > Eric indicates that Walter Bright believes, in c++: > > that instantiating a template is inherently expensive, and certain > features of the C++ language (ADL, partial specialization, etc.) > force that to be the case. > > Walter, if Eric is remembering correctly, could you provide a little more explanation on why this is so or provide a link to some document supporting this conclusion? > > TIA. > > -regards, > Larry "C++ Compilation Speed" by Walter Bright: http://www.drdobbs.com/cpp/c-compilation-speed/228701711 Note the #7. |
November 03, 2012 Re: why are c++ template instantiations inherently slow? | ||||
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Posted in reply to Nick Sabalausky | On 11/01/12 04:29, Nick Sabalausky wrote:
> On Tue, 09 Oct 2012 15:59:26 -0500
> evansl <cppljevans@suddenlink.net> wrote:
>
>> In this post:
>>
>> http://article.gmane.org/gmane.comp.lib.boost.devel/189925
>>
>> Eric indicates that Walter Bright believes, in c++:
>>
>> that instantiating a template is inherently expensive, and certain
>> features of the C++ language (ADL, partial specialization, etc.)
>> force that to be the case.
>>
>> Walter, if Eric is remembering correctly, could you provide a little more explanation on why this is so or provide a link to some document supporting this conclusion?
>>
>> TIA.
>>
>> -regards,
>> Larry
>
> "C++ Compilation Speed" by Walter Bright: http://www.drdobbs.com/cpp/c-compilation-speed/228701711
>
> Note the #7.
>
Thanks very much for the link Nick.
I read it and now I'm heavily leaning toward
converting to D now.
However, I saw no mention of ADL and partial specialization. Is there some other reference explaining why these lead to slow compile times?
-regards,
Larry
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November 04, 2012 Re: why are c++ template instantiations inherently slow? | ||||
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Posted in reply to evansl | On Sat, 03 Nov 2012 12:36:00 -0500
evansl <cppljevans@suddenlink.net> wrote:
> On 11/01/12 04:29, Nick Sabalausky wrote:
> >
> > "C++ Compilation Speed" by Walter Bright: http://www.drdobbs.com/cpp/c-compilation-speed/228701711
> >
> > Note the #7.
> >
> Thanks very much for the link Nick.
> I read it and now I'm heavily leaning toward
> converting to D now.
>
> However, I saw no mention of ADL and partial specialization. Is there some other reference explaining why these lead to slow compile times?
>
Not that I know of, but I would assume it's because (IIUC) those are heavily template-oriented things which, in turn, are slow in C++ because of the reasons he described. You could try asking over on the "digitalmars.D" newsgroup, as that tends to get a lot more traffic (same NNTP server as here, ie, news.digitalmars.com).
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