WatchHisBeardGrow.com Blog

Java-like instanceof

Oct 04, 2009

So I was hoping c++ had a Java-like instanceof function. It didnt as far as I could find... Lame. Instead I have to include an enumerated value in all of my subclasses to determine which subclass of a light i am dealing with... This sucks.


enum type {AMBIENT, DIFFUSE, PHONG};

class Light{
public:
	Light(unsigned int color, float strength, type lightType);
	unsigned int getColor();
	type getType();
	virtual void update(vector meshes);
protected:
	type lightType;
	unsigned int color;
	float strength;
};

Thoughts, anyone? Is there a better way?

Oct 04, 2009 - 7:36 pm

Aaron Sarazan

http://www.gamedev.net/community/forums/topic.asptopicid=98218&whichpage=1&512442This article has a pretty decent discussion regarding it. Our engine goes the id route that you've got, although really you don't need to include it in the constructor. Just make it a static with a virtual getter.

Oct 04, 2009 - 7:40 pm

Andrew

Ah, not bad. Thanks Aaron.

Oct 05, 2009 - 6:19 am

Paul

When you find that you need to ask what the runtime type of an object is, refactor so that it is not necessary. In this specific example, I would rather model ambient, diffuse, and phong as lighting strategies than types of lights.

Oct 05, 2009 - 6:30 am

Andrew

Paul, I completely forgot about the Strategy design pattern. Looks like I may need to pick up Holub again and refresh. I am going to give this more thought - Strategy should work and will be ten times better than this.

How on earth do you keep all of these design patterns fresh in your head