Boost bind and boost function, storing functions with arguments in a vector and then executing them

Question

Sorry for the badly-worded title.

I've been looking through the documentation, but I cannot find anything that might solve this problem I have.

Basically I want to store several function1<void, void*> , with arguments provided, in a vector, and then execute them at a later stage.

This is what I want to accomplish:

typedef boost::function1<void, void*> Task;

Vector<Task> mScheduledTasks;
int MyArg = 5;

void SomeTask(void* arg)
{
    // ....
}

void AddSomeTasks()
{
    // nevermind that MyArg is globally accessible
    for (int i = 0; i<5; i++)
        mScheduledTasks.push_back(boost::bind(&SomeTask, _1), (void*)&MyArg);
}

void ExecuteTask()
{
    Task task = mScheduledTasks.front();
    task();
}

Now executing task() it wants me to pass an argument, but I passed it in AddSomeTasks? Why is it not using that? Or I have missunderstod the usage of boost::bind?

Thanks

Answer 1

your Task type wants an argument, it should have been boost::function0<void>. When you bind an argument, the returned (bound) callable object is of arity 0, not 1.

Also, to bind an argument you supply it to the call to boost::bind, the _1 etc are for arguments that are left unbound, not what you want here.

Something like (untested):

typedef boost::function0<void> Task;

Vector<Task> mScheduledTasks;
int MyArg = 5;

void SomeTask(void* arg)
{
    // ....
}

void AddSomeTasks()
{
    // nevermind that MyArg is globally accessible
    for (int i = 0; i<5; i++)
        mScheduledTasks.push_back(boost::bind(&SomeTask, (void*)&MyArg));
}

void ExecuteTask()
{
    Task task = mScheduledTasks.front();
    task();
}