Use of boost coroutine2 without lambdas

Question

I guess this is the first time I couldn't manage to find an already answered question in here, and I could really use some help if anyone have successfully used boost coroutine2 lib without lambdas. My problem, sumarized:

class worker {
...
void import_data(boost::coroutines2::coroutine
<boost::variant<long, long long, double, std::string> >::push_type& sink) {
...
sink(stol(fieldbuffer));
...
sink(stod(fieldbuffer));
...
sink(fieldbuffer); //Fieldbuffer is a std::string
}
};

I intend to use this as a coroutine from inside another class, that has the task of putting each yielded value in its place, so I tried to instantiate an object:

worker _data_loader;
boost::coroutines2::coroutine<boost::variant<long, long long, double, string>>::pull_type _fieldloader
        (boost::bind(&worker::import_data, &_data_loader));

but that wont compile:

/usr/include/boost/bind/mem_fn.hpp:342:23:
error: invalid use of non-static member function of type 
‘void (worker::)(boost::coroutines2::detail::push_coroutine<boost::variant<long int, long long int, double, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&)’

Could someone shed any light in this problem?

sehe · Accepted Answer · 2017-09-27T08:03:13.797

This has nothing to do with Boost Coroutine.

It is just about bind with a member function. You forgot to expose the unbound parameter:

boost::bind(&worker::import_data, &_data_loader, _1)

Live On Coliru

#include <boost/coroutine2/all.hpp>
#include <boost/variant.hpp>
#include <boost/bind.hpp>
#include <string>

using V    = boost::variant<long, long long, double, std::string>;
using Coro = boost::coroutines2::coroutine<V>;

class worker {
  public:
    void import_data(Coro::push_type &sink) {
        sink(stol(fieldbuffer));
        sink(stod(fieldbuffer));
        sink(fieldbuffer); // Fieldbuffer is a std::string
    }

    std::string fieldbuffer = "+042.42";
};

#include <iostream>
int main() 
{
    worker _data_loader;
    Coro::pull_type _fieldloader(boost::bind(&worker::import_data, &_data_loader, _1));

    while (_fieldloader) {
        std::cout << _fieldloader.get() << "\n";
        _fieldloader();
    }
}

Prints

42
42.42
+042.42

Use of boost coroutine2 without lambdas

1 Answers1