Re: Callbacks using a 3rd party library in C

[Luiz Henrique de Figueiredo <lhf@...>]

> Assume a third party C library to wich I can register any number of 
> callbacks that this library will sometimes call, like:

This is a problem that frequently arises in GUI toolkits. The solution depends
heavily on the signature of callback functions. It certainly helps when
they have a fixed signature that has room for user-supplied data. When this
happens, you can register a *fixed* dispatcher C function for all callbacks
adding enough information in the user-supplied data to be able to disptach to
Lua when the callback is called.

When the signatures of callback functions vary, you're stuck with registering
a dispatcher for each type. When the signatures do not have room for
user-supplied data, you're stuck with global Lua states and possibly more.