There is a special place in hell for people who define C callback interfaces that do not take a context parameter.
@david_chisnall indeed - it should not be necessary to use libffi or similar to generate a closure just to use a damn callback cleanly.
@david_chisnall Also for people who generate error or log messages without context (this is just a special case of a callback)
@david_chisnall context is all you need
@david_chisnall I've always called it clientData because that's what it was called at Xerox where I learned about it. Context is better!
