ofxBox2d Custom Data deletion about ofxbox2d HOT 2 CLOSED

I'll comment "in general", without knowing the specifics of your case, or Box2d user data. In libraries in general (and I'm sure Box2d is the same), user data is "user" data because the library has no idea what it is. A user data pointer is just a handy place to put "whatever you want", so you can access something in your own code when you get an event (for example) from the library. Box2d (or ofxBox2d) can't "free" it, because it doesn't know if it was allocated on the heap (using malloc, or new, for example), on the stack (e.g. a pointer to a global variable), or whether it's just a "tag" you use for your own purposes (e.g. an index into an array). It's "user" data, so it's up to the user to deal with it properly.

If you set something -- which you'd allocated yourself (using new, for example) -- as Box2d user data, you'd need to release it yourself (e.g. using delete). The library doesn't assume anything about the user data. Setting it to NULL on destruction of the Box2d primitive wouldn't do any harm, but wouldn't free your object, either.

from ofxbox2d.

Thanks Glen.

Also found this on the OF Forum about this subject and freeing memory: "box2d contact listening and userdata"
http://forum.openframeworks.cc/index.php?topic=3441.0

Maybe it would be nice to get this include in the Custom Data & ContactListener examples.

from ofxbox2d.