When i refreshed the page the day 2 video was in its place

So not where can i get hold of day 1 video ?

posted by SmileBig

posted by Chris

posted by andrei_alexandrescu

C

posted by Charles

posted by Charles

template <
    typename T,
    template <
        template<class...> class... Policies
    >
>
class ICantBelieveItsNotButter;

Either a missing "class Name" or the "template< >" around the policies is too much. So much for "My code has no mistakes".

Other than that, great talk. Enjoyed it very much. Though one thing I'd certainly like to see from the standard side is better (read: smarter) pack expansion, so we don't need to resort to recursion all that often if the expansion is actually really trivial (say, + instead of a comma):

template<class T, class Head, class... Operands>
struct var_add{
  static T const value = Head::value + Operands::value...
  //                     pattern -- (                 )
};

Whereas the recursive (and current) way would look something like this:

template<class T, class Head, class... Tail>
struct var_add{
  static T const value = Head::value + var_add<Tail...>::value;
};

template<class T, class Head>
struct var_add<T, Head>{
  static T const value = Head::value;
};

(I hope the formatting works...)

posted by c9xeo

    void fun(void (*pFun)(int xyz));

is the same as

    void fun(void (*pFun)(int));

posted by andrei_alexandrescu

posted by c9xeo

template <
  typename T,
  template<class...> class... Policies
>
class ICantBelieveItsNotButter;

Thanks for the correction!

posted by andrei_alexandrescu

posted by zbigg

posted by Enno

Since conferences always seem to bring a lot of "where's the video" comments, could you add some sort of status indicator on these posts?  Something like:

• Talk has not happened yet
• Talks is airing live
• Talk is past and was recorded, is now in processing (ideally with an ETA, but you can only do so much)
• Talk uploaded for perpetual on-demand access by Niners

posted by Lars Kemmann

That pack expansion occurs when it is an argument of another function that you are calling (see Slide 8/34 where the pack expansion of Ts and vs occurs on std::forward when calling the gun function).

Here's another example:

#include <iostream>

template < typename TYPE >
inline TYPE g ( TYPE value ) {
    return value;
}

inline void f () {
    //
}

template < typename HEAD_TYPE, typename ... TAIL_TYPE_PACK >
inline void f ( HEAD_TYPE head_value, TAIL_TYPE_PACK ... tail_value_pack ) {
    std::cout << head_value << '\n';
    f( g( tail_value_pack ) ... );
}

int main () {
     f( 1.0, "2", 3, "four" );
    return 0;
}

The code (I believe) you are interested in is the line ...

f( g( tail_value_pack ) ... );

f( g( "2" ), g( 3 ), g( "four" ) );

f(  );

Using MinGW's g++ version 4.6.2, you can compile and run this using:

g++ -o main.exe -std=c++0x -march=native -O3 -Wall -Wextra -Werror main.cpp && ./main.exe

1
2
3
four

I believe this is covered in section 14.5.3 point 5 ... it seems to be listed in the exampe as:

f(const_cast<const Args*>(&args)...); // OK: “Args” and “args” are expanded

Hope This Helps,
Joshua Burkholder

posted by Burkholder

4 days ago, Lars Kemmann wrote

Dear C9 Team,

Since conferences always seem to bring a lot of "where's the video" comments, could you add some sort of status indicator on these posts?  Something like:

• Talk has not happened yet
• Talks is airing live
• Talk is past and was recorded, is now in processing (ideally with an ETA, but you can only do so much)
• Talk uploaded for perpetual on-demand access by Niners

Good idea!

posted by Charles

posted by KikiAlex