channel01.cpp : /usr/include/stlab/concurrency/variant.hpp:37:10: fatal error: boost/variant.hpp: No such file or directory

[marcoippolito]

First example channel taken here: https://github.com/FelixPetriconi/accu2017_course/tree/master/Channels

`#include <stlab/concurrency/channel.hpp>
 #include <stlab/concurrency/default_executor.hpp>
  #include <iostream>

  int main() {
    stlab::sender<int> send;       // sending part of the channel
    stlab::receiver<int> receiver; // receiving part of the channel
    std::tie(send, receiver) =     // combining both to a channel
    stlab::channel<int>(stlab::default_executor);

    auto printer =
      [](int x){ std::cout << x << '\n'; };       // stateless process

    auto printer_process =
      receiver | printer;                                  // attaching process to the receiving
                                                                                                                             // part
    receiver.set_ready();          // no more processes will be attached
                                                                                                                             // process starts to work
    send(1); send(2); send(3);     // start sending into the channel
    int end; std::cin >> end;      // simply wait to end application
    return 0;
  }
 `

When compiling:

`accu2017_course-master/Channels$ g++ -std=c++17 channel01.cpp -ochannel01`

`In file included from /usr/include/stlab/concurrency/channel.hpp:26:0,
                 from channel01.cpp:1:
 /usr/include/stlab/concurrency/variant.hpp:37:10: fatal error: boost/variant.hpp: No such file or    
 directory
  #include <boost/variant.hpp>
           ^~~~~~~~~~~~~~~~~~~
 compilation terminated.
`

Do I have to install boost even if I use C++17 ?

Marco

[FelixPetriconi]

I think you have found a hole in the lib. Could you try to add in file stlab/concurrency/config.hpp below line 58 (#define STLAB_TASK_SYSTEM STLAB_TASK_SYSTEM_PORTABLE) the lines

#if __cplusplus >= 201703L
#define STLAB_CPP_VERSION 17
#endif

? I think it does not recognize that it should work with C++17 on Linux.

[marcoippolito]

After adding the suggested lines below line 58 in file /usr/include/stlab/concurrency/config.hpp :

`// Default configuration

#ifndef STLAB_TASK_SYSTEM
#define STLAB_TASK_SYSTEM STLAB_TASK_SYSTEM_PORTABLE
#if __cplusplus >= 201703L
#define STLAB_CPP_VERSION 17
#endif
#endif
`

The compilation gives the following error messages:

CompilationErrors.txt

[FelixPetriconi]

I found the problem: std::optional does not allow an instantiation of a reference type (compared to boost::optional) So you either have to attach the process directly as written below or put it into a struct, that implements the operator().

`
#include <stlab/concurrency/channel.hpp>
#include <stlab/concurrency/default_executor.hpp>
#include

int main() {
stlab::sender send; // sending part of the channel
stlab::receiver receiver; // receiving part of the channel
std::tie(send, receiver) = // combining both to a channel
stlab::channel(stlab::default_executor);

auto printer_process =
  receiver | [](int x){ std::cout << x << '\n'; };         // attaching process to the receiving
                                                                                   // part
receiver.set_ready();          // no more processes will be attached
                                             // process starts to work
send(1); send(2); send(3);     // start sending into the channel
int end; std::cin >> end;      // simply wait to end application
return 0;

}
`

[marcoippolito]

After directly attaching the process to the receiving part, the error messages changed
CompilationErrors2.txt

[FelixPetriconi]

You have to add to channel.hpp an #include
It depends a bit to the distributions, if you have to add it manually.
I will change it in the repo.

[marcoippolito]

After adding in /usr/include/stlab/concurrency/channel.hpp

 `#include <assert>`

`/Channels$ g++ -std=c++17 channel01.cpp -pthread -ochannel01
 ./channel01
1
2
3
`

I close the issue

[FelixPetriconi]

Fixed with PR #148

[FelixPetriconi]

Reopend for release note

[FelixPetriconi]

Fixed in 1.2.0