Is there a way to create a callback in Python?

Question

Also is there a way to detect if the user presses a key in Python that works on most OS's? I've only seen 1 method and that only works in Python 2.6 and less. If you get the key, can you store it in a variable?

Answer 1

What is usually meant by "a callback" is a function object. In Python, functions are first class objects. You just use the function name without the parentheses.

def my_function():
 print "Executing my_function"

b = my_function # b is now a function object

b() 

Likewise, instead of storing it in a global, you might pass it to a method which stores it as an object attribute, or whatever.

Also of interest is that you can easily create partial functions, where some of the parameters are already decided. See the docs for functools.partial

And if you're trying to use a method as a callback, you can store the bound-method, which is effectively a partial including the self parameter.

Finally, don't forget lambda functions, which can be useful if you're trying to create a simple function and don't need a name for it.

Answer 2

Your question is somewhat vague.
Are you asking for a function that waits for the user to press a key and then returns the key that was pressed? Or are you asking for a function that detects whether a key has been pressed at all?