CODEWITHSUNDEEP
c++
Nelson McCullough
Nelson McCullough

Reputation: 63

storing, parsing through and executing stored member functions

I'm currently working on some code and need to make something like an event handler that I can register explicit events and store them into a vector that I can loop through in my main listen() function. I'm missing something about pointers that I cant pinpoint with docs and a google search and need help figuring out why my compilers asking for a pointer to a member.

I've tried creating a typedef with a member function definition but I have the problem of it not compiling currently with a "non standard syntax, put an & to create a pointer to a member." error.

class Obj {
private:
    typedef int (Obj::*Event) (std::vector<std::string> in);
    std::vector<Event> events;

    int exampleEvent(std::vector<std::string> input);
public:
    Obj();

    int regEvent(Event ev);
    int listen();
}

example event code

int Obj::exampleEvent(std::vector<std::string> input)
{
    // heres my app logic
    return 0;  
}

register events in constructor

Obj::Obj()
{
    regEvent(exampleEvent); // exampleEvent: non-standard syntax; use 
                            //'&' to create a pointer to member
}

listen, and add event to vector.

int Obj::regEvent(Event ev)
{
    events.push_back(ev);
    return 0;
}

// listen for command input
int Obj::listen()
{ 
    // get input
    string str;
    getline(cin, str);
    vector<string> input = split(str, " ");

    // loop through events
    for (auto ev : events)
    {
    ev(input); // <-- Term does not evaluate to function taking 1 arg.
    }
    return 0;
}

Upvotes: 0

Views: 37

Answers (2)

bruno
bruno

Reputation: 32586

Obj::Obj()
{
    regEvent(exampleEvent); // exampleEvent: non-standard syntax; use 
                            //'&' to create a pointer to member
}

must be

Obj::Obj()
{
    regEvent(&Obj::exampleEvent); 
}

and

for (auto ev : events)
{
ev(input); // <-- Term does not evaluate to function taking 1 arg.
}

must be

for (auto ev : events)
{
  (this->*ev)(input);
}

Upvotes: 1

Jarod42
Jarod42

Reputation: 217265

Exxpected syntax is:

regEvent(&Obj::exampleEvent);

Upvotes: 1

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