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    <p>You're getting pretty close to the way most games actually do it (although performance expert curmudgeon Mike Acton <a href="http://macton.smugmug.com/gallery/8936708_T6zQX#593426709_ZX4pZ" rel="noreferrer">often gripes about that</a>).</p> <p>Typically you'd see something like this</p> <pre><code>class CEntity { public: virtual void draw() {}; // default implementations do nothing virtual void update() {} ; virtual void handleinput( const inputdata &amp;input ) {}; } class CEnemy : public CEntity { public: virtual void draw(); // implemented... virtual void update() { do_ai_stuff(); } // use the default null impl of handleinput because enemies don't care... } class CPlayer : public CEntity { public: virtual void draw(); virtual void update(); virtual void handleinput( const inputdata &amp;input) {}; // handle input here } </code></pre> <p>and then the entity manager goes through and calls update(), handleinput(), and draw() on each entity in the world. </p> <p>Of course, having a whole lot of these functions, most of which do nothing when you call them, can get pretty wasteful, especially for virtual functions. So I've seen some other approaches too. </p> <p>One is to store <em>eg</em> the input data in a global (or as a member of a global interface, or a singleton, etc). Then override the update() function of enemies so they do_ai_stuff(). and the update() of the players so that it does the input handling by polling the global.</p> <p>Another is to use some variation on the <a href="http://en.wikipedia.org/wiki/Observer_pattern" rel="noreferrer">Listener pattern</a>, so that everything that cares about input inherits from a common listener class, and you register all those listeners with an InputManager. Then the inputmanager calls each listener in turn each frame:</p> <pre><code>class CInputManager { AddListener( IInputListener *pListener ); RemoveListener( IInputListener *pListener ); vector&lt;IInputListener *&gt;m_listeners; void PerFrame( inputdata *input ) { for ( i = 0 ; i &lt; m_listeners.count() ; ++i ) { m_listeners[i]-&gt;handleinput(input); } } }; CInputManager g_InputManager; // or a singleton, etc class IInputListener { virtual void handleinput( inputdata *input ) = 0; IInputListener() { g_InputManager.AddListener(this); } ~IInputListener() { g_InputManager.RemoveListener(this); } } class CPlayer : public IInputListener { virtual void handleinput( inputdata *input ); // implement this.. } </code></pre> <p>And there are other, more complicated ways of going about it. But all of those work and I've seen each of them in something that actually shipped and sold.</p>
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    1. COMan, the guy in that link was truly terrible.
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    2. COMaybe, but he's also why Ratchet & Clank never went below 60fps.
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    3. CO@DeadMG: well, he points out some real issues, in terms of performance and design. He also seems to have an irrational dislike of C++, and squeezed in some completely pointless rants as well (like the one against references). Still, filter out the bullshit, and the performance advice is pretty solid.
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