Thread: Need help with vectors of std::function

I'm tying to make what I guess would be described as an event system. A dynamic array of functions that get all get called when a single function is called. My problem is that the functions are not getting called and I can't figure out why. I'm not experienced with C++, I'm used to using c# and before that Java.

Here's my code, well the relevant snippets.

Code:

    static std::vector<std::function<void()>> * renderFunctions = new std::vector<std::function<void()>>;

//

    std::vector<std::function<void()>>::iterator it;
    for (it = renderFunctions->begin(); it < renderFunctions->end(); it++) {
        (*it)();
    }

//

    std::function<void(void)> x = testRender;
    Display::renderFunctions->push_back(x);

//

void testRender() {
    glUseProgram(shader);
    glBindVertexArray(VAO);
    glDrawArrays(GL_TRIANGLES, 0, 3);
    glBindVertexArray(0);

    std::cout << "I'm not getting called, argghh!";
}

The iterator is getting called from a loop.

Not enough info to go on - it works for me.

Code:

#include <iostream>
#include <vector>
#include <functional>

typedef std::function<void()> f_t;

void foo () {
  std::cout << "Yay!" << std::endl;
}

int main ( ) {
  std::vector<f_t> *renderFunctions = new std::vector<f_t>;
  f_t x = foo;
  renderFunctions->push_back(x);
  std::vector<f_t>::iterator it;
  for ( it = renderFunctions->begin() ; it != renderFunctions->end(); ++it ) {
    (*it)();
  }
}

$ g++ -std=c++11 foo.cpp
$ ./a.out 
Yay!

Still no problem.

Code:

#include <iostream>
#include <vector>
#include <functional>

typedef std::function<void()> f_t;

namespace wibble {
  void foo () {
    std::cout << "Yay!" << std::endl;
  }
}

int main ( ) {
  std::vector<f_t> *renderFunctions = new std::vector<f_t>;
  f_t x = wibble::foo;
  renderFunctions->push_back(x);
  std::vector<f_t>::iterator it;
  for ( it = renderFunctions->begin() ; it != renderFunctions->end(); ++it ) {
    (*it)();
  }
}

You're just going to have to post a real compilable example that doesn't work for you for us to test.

Random "it doesn't work" is a pointless 20 questions game.

Code:

		for (it = updateFunctions->begin(); it < updateFunctions->end(); it++) {
			*it;

Why does this look nothing like the code I posted?

First of all, using < in the loop only works if your container supports random access. If you changed to a list say, then the loop is suddenly broken.
Using != means you no longer care about container choice.

Second, just saying *it does nothing.

If I break my code the way yours is broken, I get nothing either.

So does this fail for you?

Code:

$ cat foo.cpp
#include <iostream>
#include <vector>
#include <functional>

typedef std::function<void()> f_t;

namespace Display {
  std::vector<f_t> * renderFunctions = new std::vector<f_t>;
  void render(); 
}

void Display::render() {
  std::vector<f_t>::iterator it;
  for ( it = renderFunctions->begin() ; it != renderFunctions->end(); ++it ) {
    std::cout << "boo" << std::endl;
    (*it)();
  }
}

void testRender () {
  std::cout << "Yay!" << std::endl;
}

int main ( ) {
  f_t x = testRender;
  Display::renderFunctions->push_back(x);
  Display::render();
}
$ g++ -std=c++11 foo.cpp
$ ./a.out 
boo
Yay!
$ 
$ g++ --version
g++-5.real (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

It's your git-repo code with all the fluff removed.
It doesn't need your namespace wrapper hackery to make it work (for me at least).

Since you're using git, why not create a test branch and start chipping away at your code (removing stuff which isn't necessary to demonstrate the problem).

When you're done, you can just delete the branch.