Re: tuples in C++11

From:
88888 Dihedral <dihedral88888@googlemail.com>
Newsgroups:
comp.lang.c++
Date:
Tue, 14 Aug 2012 13:43:52 -0700 (PDT)
Message-ID:
<64a0c925-ba9b-4aba-9a75-55ed904d0768@googlegroups.com>
Single Stage to Orbit=E6=96=BC 2012=E5=B9=B48=E6=9C=8815=E6=97=A5=E6=98=9F=
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Hello!
 
 
 
Suppose I have the following:
 
 
 
int main()
 
{
 
        typedef boost::tuple<int, int, int> tuple3;
 
        std::vector<tuple3> tuples;
 
 
 
        tuples.push_back(tuple3(1, 2, 3));
 
        tuples.push_back(tuple3(7, 8, 9));
 
        tuples.push_back(tuple3(4, 5, 6));
 
 
 
        for (auto& i : tuples)
 
                std::cout << i.get<0>() << " " << i.get<1>() << " " <<
 
i.get<2>() << '\n';
 
 
 
        return 0;
 
}
 
 
 
Is it even possible to have something like this:
 
 
 
for (auto& i : tuples)
 
{
 
        for (unsigned j = 0; j < 3; ++j)
 
        {
 
                std::cout << i.get<j>();
 
                if (j < 3)
 
                        std::cout << " ";
 
        }
 
 
 
        std::cout << '\n';
 
}
 
 
 
When I try it, GCC 4.6.3 says it's illegal to have an non constant
 
expression as in 'i.get<j>'. Are there any workarounds for this one?
 
 
 
Thanks!
 
--
 
Tactical Nuclear Kittens


Single Stage to Orbit=E6=96=BC 2012=E5=B9=B48=E6=9C=8815=E6=97=A5=E6=98=9F=
=E6=9C=9F=E4=B8=89UTC+8=E4=B8=8A=E5=8D=882=E6=99=8217=E5=88=8626=E7=A7'=
=E5=AF=AB=E9=81=93=EF=BC=9A

Hello!
 
 
 
Suppose I have the following:
 
 
 
int main()
 
{
 
        typedef boost::tuple<int, int, int> tuple3;
 
        std::vector<tuple3> tuples;
 
 
 
        tuples.push_back(tuple3(1, 2, 3));
 
        tuples.push_back(tuple3(7, 8, 9));
 
        tuples.push_back(tuple3(4, 5, 6));
 
 
 
        for (auto& i : tuples)
 
                std::cout << i.get<0>() << " " << i.get<1>() << " " <<
 
i.get<2>() << '\n';
 
 
 
        return 0;
 
}
 
 
 
Is it even possible to have something like this:
 
 
 
for (auto& i : tuples)
 
{
 
        for (unsigned j = 0; j < 3; ++j)
 
        {
 
                std::cout << i.get<j>();
 
                if (j < 3)
 
                        std::cout << " ";
 
        }
 
 
 
        std::cout << '\n';
 
}
 
 
 
When I try it, GCC 4.6.3 says it's illegal to have an non constant
 
expression as in 'i.get<j>'. Are there any workarounds for this one?
 
 
 
Thanks!
 
--
 
Tactical Nuclear Kittens


Do you plan to compress imutable objects into a serializable frozen file in=
 
the hard disk or your own heap manager?

If you are not planning to do that then I don't think immutable tuples
are very helpful.

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