Re: [Boost-users] [fusion] push_back / pop_back

Subject: Re: [Boost-users] [fusion] push_back / pop_back
From: Christopher Schmidt (mr.chr.schmidt_at_[hidden])
Date: 2011-10-25 10:31:50

Daniel Bradburn <moagstar_at_[hidden]> writes:

> Hi,
>
> I am trying to do the following:
>
> #include <string>#include <boost/fusion/tuple.hpp>#include
> <boost/fusion/include/push_back.hpp>#include
> <boost/fusion/include/pop_back.hpp>
>  int main(int argc, char* argv[])
> {
>     typedef boost::fusion::tuple<int> T1;
>     typedef boost::fusion::result_of::push_back<const T1, std::string>::type T2;
>
>     T1 a(0);
>     T2 b(boost::fusion::push_back(a, std::string("")));
>
>     boost::fusion::get<0>();

fusion::joint_view, which is returned by fusion::push_back, does not
implement the random access concept.  Use fusion::front or fusion::deref
x fusion::begin.

>
>     T1 c(boost::fusion::pop_back(b));

fusion::pop_back requires the sequence to be bidirectional.
fusion::joint_view isn't.

>     return 0;
>
> }
>

[...]

        Christopher