4

Hi I am a noob in C++ trying to modify an existing native node module.

I am trying to add couts inside the module to print info I think is useful for me. 

NAN_METHOD(Context2d::SetFillRule){
  Context2d *context = Nan::ObjectWrap::Unwrap<Context2d>(info.This());
  cairo_t *ctx = context->context();
  String::Utf8Value str(info[0]);
  cout << "set method called";
  ...
}

The previous method is working but the cout is never shown. Is it lost/shown during the node-gyp build? Have I done something wrong? is there a way to accomplish it?

ZachB
  • 13,051
  • 4
  • 61
  • 89
cs04iz1
  • 1,737
  • 1
  • 17
  • 30
  • 1
    How is the binary launched? Can we have some context? Are you sure to get through this particular method? Did you try to attach a debugger? – YSC Dec 17 '15 at 15:35
  • I configure and build it using the node-gyp as It is proposed. Yes the method is working for sure. The changes that should be made are done. The cout is the only thing I cant see. No I havent tested a debugger. – cs04iz1 Dec 17 '15 at 15:38
  • 1
    I guess the standard output is redirected to a log file. If you're under a *nix, you could `lsof pid` your process to find this log file. – YSC Dec 17 '15 at 15:50

5 Answers5

3

I am trying to learn N-API to make an addon for a nodejs project and just had the same issue. Adding #include <iostream> made std::cout available for use in my code. When I run my code by calling node path_to_file.js as I would for any nodejs project, it successfully prints my data to the console. I know that you are using NAN and probably already overcame this issue a long time ago, but I felt it was important to give this answer since this showed up in my search results and there was not a good answer for beginners like me.

kevinGodell
  • 81
  • 1
  • 6
0

I'd suggest writing it to a log file instead (redirecting std::cout is a pain).

std::ofstream logFile("logfile.txt");
logFile << "set method called";
David Haim
  • 25,446
  • 3
  • 44
  • 78
0

std::cout << in a Node.js C++ add-on is supposed to normally print to the console (the stdout of the node process).

If it doesn’t appear, it’s likely segmentation faults due to poor memory (instance lifespan) management. It kills the entire node process silently.

Константин Ван
  • 12,550
  • 7
  • 61
  • 73
-1

The cout << "some text" will only works if you launch your binary straight from the command line. I think it is not the case, as appears you are using it inside node. So you should find some log output method from node libraries.

Flávio Filho
  • 475
  • 4
  • 14
-1

If it is in windows you can try to make another console window.Then bind your contex to that window and redirect the print to there.

or write into a file.

Raimbek Rakhimbek
  • 67
  • 1
  • 12