Writing wrappers for other programming languages would be easier if user data could be specified for callbacks the engine uses. Just like the Newton engine handles this. Without support for user data it´s often necessary to do ugly workarounds.

User data for callbacks - do you mean function parameters? You can use callback functions with as many parameters as you want.

How can I use callbacks with as many parameters as I want?

I mean something like this for example (pseudocode):



Hm... Well, I could use a skill in this case but that´s not very elegant and I would have to warn every user of the wrapper with "NEVER USE SKILL100 YOURSELF!" or something.

Hmm, I know that I'm very stupid, but why are you assigning a callback function to an event, and what is your "eventuserdata" supposed to mean?

Callback functions are usually passed to a library in function arguments. They are stored in a function pointer and then called like any other function.

Maybe I use the wrong terminology but isn´t this a callback? I tell the engine which function to call when a collision happens. I don´t pass the callback to a library in function arguments like you wrote but assign the function pointer to my.event.

Since C can only call C functions I have to do something like above if I want to expose the callback functionality to another language like Python. I want to write a Python wrapper and I want achieve that collision callbacks can also be written in Python.

Ah, ok. Your "c_callback" is not a callback, it's an event function. You can pass any parameters to callback functions, but the parameters for event functions are specified and depend on the kind of event.

You event function can just collect the required data from the 'my' entity and then call the python function.