Re: [boost] Workaround for compiler bugs

Subject: Re: [boost] Workaround for compiler bugs
From: Edward Diener (eldiener_at_[hidden])
Date: 2010-12-09 08:23:12

On 12/9/2010 5:35 AM, Anthony Williams wrote:
> Edward Diener<eldiener_at_[hidden]>  writes:
>
>> I will continue to look for a workaround for VC9 and earlier, as I
>> think my library should be usable by VC9, VC8, and perhaps
>> VC7.1. Thanks for your neat solution for VC10 !
>
> The following works with VC8, VC10 and g++ 4.4. It causes an Internal
> Compiler Error with VC7.1 though :-(

Thanks, Anthony ! Works with VC9 also. I will play around more with 
VC7.1 but I will not worry if I can not get it to work there as that is 
a pretty old version of VC now. My original code works with gcc 4+ so 
gcc is not an issue.

>
> #include<iostream>
>
> typedef char small_type;
>
> struct large_type
> {
>      small_type dummy[2];
> };
>
>
> template<bool,typename T>
> struct enable_if;
>
> template<typename T>
> struct enable_if<true,T>
> {
>      typedef T type;
> };
>
> template<typename T,typename DT>
> struct has_member_cMem_of_type
> {
>      template<typename U>
>      static small_type check2(DT (U::*));
>      template<typename U>
>      static large_type check2(U);
>
>      template<typename U>
>      static typename enable_if<
>          sizeof(check2(&U::cMem))==sizeof(small_type),
>          small_type>::type
>      has_matching_member(int);
>      template<typename U>
>      static large_type has_matching_member(...);
>
>      static const bool value=sizeof(has_matching_member<T>(0))==sizeof(small_type);
> };
>
>
> struct Gipf { };
>
> struct Dvonn {
>      Gipf cMem;
> };
>
> struct Tzaar {
>      int cMem;
> };
>
> struct Yinsh {
>      int Zertz;
>      void cMem();
> };
>
> struct Derived:
>      Dvonn
> {};
>
>
> int main() {
>      std::cout<<"one:"<<has_member_cMem_of_type<Dvonn, Gipf>::value<<std::endl;
>
>      std::cout<<"two" ":"<<!has_member_cMem_of_type<Dvonn,  int>::value<<std::endl;
>
>      std::cout<<"three" ":"<<!has_member_cMem_of_type<Tzaar, Gipf>::value<<std::endl;
>      std::cout<<"four" ":"<<  has_member_cMem_of_type<Tzaar,  int>::value<<std::endl;
>
>      std::cout<<"five" ":"<<!has_member_cMem_of_type<Yinsh, Gipf>::value<<std::endl;
>      std::cout<<"six" ":"<<!has_member_cMem_of_type<Yinsh,  int>::value<<std::endl;
>
>
>      std::cout<<"seven" ":"<<has_member_cMem_of_type<Derived, Gipf>::value<<std::endl;
>      std::cout<<"eight" ":"<<!has_member_cMem_of_type<Derived,  int>::value<<std::endl;
> }
>
> Anthony