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C++0x - nested initializer lists?

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  C++0x - nested initializer lists? er <er.ci.2020@gmail.com> - 2011-06-22 10:15 -0700
    Re: C++0x - nested initializer lists? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-06-23 09:55 -0400
      Re: C++0x - nested initializer lists? er <er.ci.2020@gmail.com> - 2011-06-23 08:03 -0700
    Re: C++0x - nested initializer lists? Saeed Amrollahi <amrollahi.saeed@gmail.com> - 2011-06-25 01:25 -0700
    Re: C++0x - nested initializer lists? Saeed Amrollahi <amrollahi.saeed@gmail.com> - 2011-06-25 07:01 -0700

#7065 — C++0x - nested initializer lists?

Hi,

This does not compile under gcc-4.4: converting to 'std::tuple<>' from
initializer list would use explicit constructor. Is it conformant
anyway? Thanks.

    {
        typedef std::tuple<s_, int> t_;
        typedef std::vector<t_> v_;
        v_ v = {
            {  "a", 1  },
            {  "b", 2  },
            {  "c", 3  },
            {  "d", 4  },
            {  "e", 5  }
        };
    }

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#7081

On 6/22/2011 1:15 PM, er wrote:
> This does not compile under gcc-4.4: converting to 'std::tuple<>' from
> initializer list would use explicit constructor. Is it conformant
> anyway? Thanks.
>
>      {
>          typedef std::tuple<s_, int>  t_;
>          typedef std::vector<t_>  v_;
>          v_ v = {
>              {  "a", 1  },
>              {  "b", 2  },
>              {  "c", 3  },
>              {  "d", 4  },
>              {  "e", 5  }
>          };
>      }

What's "s_"?

V
-- 
I do not respond to top-posted replies, please don't ask

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#7084

> What's "s_"?
>
> V
> --
> I do not respond to top-posted replies, please don't ask

Sorry,

typedef std::string s_;

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#7146

On Jun 22, 8:15 pm, er <er.ci.2...@gmail.com> wrote:
> Hi,
>
> This does not compile under gcc-4.4: converting to 'std::tuple<>' from
> initializer list would use explicit constructor. Is it conformant
> anyway? Thanks.
>
>     {
>         typedef std::tuple<s_, int> t_;
>         typedef std::vector<t_> v_;
>         v_ v = {
>             {  "a", 1  },
>             {  "b", 2  },
>             {  "c", 3  },
>             {  "d", 4  },
>             {  "e", 5  }
>         };
>     }

Hi

Sorry for late feedback. Your code doesn't compile under g++ 4.6.0
too,
and I don't know it is standard conformance or not,
but if you have tuple with two 2 arguments you can use pair, actually
the following code is compiled and run:

#include <string>
#include <utility>
#include <vector>
#include <algorithm>
#include <iterator>
#include <iostream>

typedef std::string s_;
typedef std::pair<s_, int> p_;
typedef std::vector<p_> v_;

v_ v = { { "a", 1},
	 { "b", 2}
       };

int main()
{
  using namespace std;
  for (v_::size_type sz = 0; sz < v.size(); ++sz) {
    cout << "{ " << v[sz].first << ", " << v[sz].second << "}" <<
'\n';
  }
  return 0;
}

I try to find the reason behind tuple and initializer list

HTH,
  -- Saeed Amrollahi

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#7154

On Jun 22, 8:15 pm, er <er.ci.2...@gmail.com> wrote:
> Hi,
>
> This does not compile under gcc-4.4: converting to 'std::tuple<>' from
> initializer list would use explicit constructor. Is it conformant
> anyway? Thanks.
>
>     {
>         typedef std::tuple<s_, int> t_;
>         typedef std::vector<t_> v_;
>         v_ v = {
>             {  "a", 1  },
>             {  "b", 2  },
>             {  "c", 3  },
>             {  "d", 4  },
>             {  "e", 5  }
>         };
>     }


I study the C++ standard document and asked your question
from C++ committee members.
You can't use initializer lists
with tuple because, tuple constructors are explicit, but the pair
constructors are not. You have to use the make_tuple function:

typedef std::vector<std::tuple<std::string, int>> v_;
v_ v = {
         std::make_tuple("a", 1),
         std::make_tuple("b", 2)
       };

HTH,
  -- Saeed Amrollahi

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