Question

In Django, can signals be used as callback functions? In other words, can the “sender” of a signal use it to gather data from another app, via the return value of send()?

Answer 1

Yes.

Both send() and send_robust() return a list of tuple pairs [(receiver, response), ... ], representing the list of called receiver functions and their response values.

Do note that this is rather a rather unorthodox mechanism for this though; if you need the return value from a function, just call it directly.