This is a generic data block that is passed along to a CallbackObject when a callback is made. It contains data specific to the particular callback type in question.
This is actually an abstract base class and contains no data. Specializations of this class will contain the actual data relevant to each callback type.
output(out: ostream) → None¶
upcall() → None¶
You should make this call during the callback if you want to continue the normal function that would have been done in the absence of a callback.