Are function pointors right for me?

[kong288]

An example of what I need this for:

Imagine I have a button class that has a method called onClick(). Whenever the button is clicked the method onClick() is called. That's all fine and dandy, but there's a problem: every object will need a different method body for their own onClick() method. So my need is this: a way to assign a a new function to a default function in an existing object so I can make my buttons actually do something.

The only thing I've found to help me with this is a function pointer, so pls tell me if you know anything better. Thanks!!

[kevinkjt2000]

You could also make custom button classes that override their parent's onClick method.

[MiiNiPaa]

Consider using function objects instead of raw pointers.

#include <functional>
#include <iostream>
#include <array>

//We cannot touch this class
class Button
{
public:
	virtual void onClick()
	{

	}
};

void click_button(Button& button)
{
	button.onClick();
}

class CustomButton: public Button
{
	const std::function<void(void)> callback;
public:
	CustomButton(std::function<void(void)> cb) : callback(std::move(cb)) {}

	virtual void onClick() override
	{
		callback();
	}
};

void meow() {std::cout << "meow";}
void beep() {std::cout << "beep";}
void clack() {std::cout << "clack";}

int main()
{
	std::array<CustomButton, 3> buttons {{{meow}, {beep}, {clack}}};
	std::cout << "Which button do you want to press? (1-3)\n";
	int i;
	std::cin >> i;
	std::cout << "Button " << i << ' ';
	click_button(buttons[i-1]);
	std::cout << "'s\n";
}

http://ideone.com/InrKwZ

[kong288]

I was trying to avoid having to make a new class for ever button. There has to be a better way than having 30 new classes for 30 new buttons that's only difference is one method.

I'll try your example. It's interesting.

[MiiNiPaa]

My example extends button adding a capability to store and change function at runtime.
Another approach would be to use templates for automatic compile0time generation.