On Thu, 28 Apr 2005 20:55:02 +0200, Daniel Frey <d.frey@gmx.de> wrote:
BTW, did you read Scott's errata?
No, I did not. But I now tested the two versions of operators.hpp with a couple of compilers (Microsoft and Borland, that's what I have got up and running at the moment, I think both are non-NRVO), and you are right: your version is 10-20% faster (checked with a wristwatch) for operations on an object containing 11 (I programmed first and counted afterwards, therefore the odd number) 32-bit integers (see object definition below). I have to admit that you are right, and I probably ought to hate that fact. I do not, though, as I would rather live in peace with my fellow human beings in general, and the Boost guys in particular. Sorry, I should probably have intialized the dialogue in a more toned-down manner. On the other hand, I do not feel that the somewhat heated tone of the discussion is all my fault. E.g. when Dave tells me that there are no programming guidelines on the homepage, I did feel sort of snubbed - he, of all persons, should know that the homepage has a link to a set of programming guidelines which at least appears to be official Boost policy. Anyway, it may be a good idea to include e.g. a reference to Scott's errata, and to the other books mentioned during the discussion on the guidelines page. Likewise, when there is a discussion about e.g. the const-ness of return values, it may be worth the effort to condense some of the points into a simple text that gets a link on the Guidelines page. -- Søren P.S.: Here is my test program. My version of operators.hpp takes about 18 seconds with the Borland compiler and 23 with the Microsoft compiler, whereas the official version takes about 15, resp. 20 seconds to run, all very approximately (no need to count the milliseconds, the assembly output also contains more "mov" instructions in my version): #include <boost/operators.hpp> class rvo:boost::addable1<rvo>{ int a,b,c,d,e,f,g,h,i,j,k; public: rvo(int x=0){a=b=c=d=e=f=g=h=i=j=k=x;} rvo& operator+=(const rvo &r){ a+=r.a; b+=r.b; c+=r.c; d+=r.d; e+=r.e; f+=r.f; g+=r.g; h+=r.h; i+=r.i; j+=r.j; k+=r.k; return *this;} }; int main(){ { rvo a(1),b(2),d(4),e(5),c; for(int i=0;i<100000000;++i) c=a+b+d+e; }