Chief Delphi - New autonomous outline tutorial

Chief Delphi (http://www.chiefdelphi.com/forums/index.php)

- Programming (http://www.chiefdelphi.com/forums/forumdisplay.php?f=51)

- - New autonomous outline tutorial (http://www.chiefdelphi.com/forums/showthread.php?t=110085)

New autonomous outline tutorial

Hi everyone,

Today I will be showing you how to implement an easy autonomous system based on callbacks/events. If anyone has done JavaScript using the jQuery library you will be quite familiar with the concept of a callback. A callback is a function (or method depending on the language) that executes after a set of code is done running.

Here is a quick jQuery example...

Code:

$(document).load(loadFunction);



var loadFunction = function() {

        alert(“Loaded”);

}

What we will be doing today will be a little bit different. We will be creating a “list” of actions we want to preform one after another. This list will be represented as a vector of functions. The first thing we have to do is define a function pointer that returns a boolean and has nothing as its paramaters.

Code:

typedef bool (Event*)(void);

That line defines a function pointer called Event that takes nothing(void) and returns a boolean(bool).

The next step will be to define a function that will execute all of our function pointers called Event.

Code:

// Function that takes a vector of Even

bool runStringOfEvents(std::vector<Event> events)

{

        // Loop through every event

        for (unsigned int i = 0 i < events.size(); i++)

        {

                // Get current event from vector

                Event event = events.at(i);

                // Execute the event and get the return value

                bool success = event();

                // If it failed return false

                if (!success)

                {

                        return false;

                }

        }

        // If all succeeded return true

        return true;

}

Now that the hard part is done we can create a function we will call two times through a list of events we pass to our runStringOfEvents function.

Code:

bool someEvent()

{

        std::cout << “Event executed” << std::endl;

        return true;

}

Now that we have our event function we can create a list in our program and execute the list of events.

Code:

int main(int argc, char** argv)

{

        // Create the vector to hold our events

        std::vector<Event> events;

        

        // Add the function to the list twice

        events.push_back(&someEvent);

        events.push_back(&someEvent);



        // Run the events

        runStringOfEvens(events);

}