Method decorator to register callbacks

Question

I'm working on a callback system in Python. The to-be callbacks are methods of a class. I register these with a decorator. Here is some pseudo class representing this:

class MyClass(ABC):
  def __init__(self):
    self.cb_stack = {}

  def register_callback(self, callback, name):
    self.cb_stack[name] = callback     

  @register_callback('mycb')
  def myCallback(self, input):
    self.do_things()

I suspect each decorator is executed by default.

I would like however for the decorator to be executed when obj.myCallback() is called, and to prevent myCallback() from executing at that moment (which should be the case here).

The alternative I have is to write it in the long form for each callback, which should work like so:

class MyClassLong(ABC):
  def __init__(self):
    self.cb_stack = {}

  def register_callback(self, callback, name):
    self.cb_stack[name] = callback     

  def myCallback(self):
    def func(self, input): 
      self.do_things()
    self.register_callback(func, 'mycb')

Notice it adds two lines of codes, so it's not really an issue but more how to make something clean. Does anyone knows how if it is achievable, and how ?

Answer 1

So both of your versions have an argument input that is ignored but to a different function both times, so I don't know what you want exactly, but if we take that out, you could simpy use:

class MyClass(ABC):
  def __init__(self):
    self.cb_stack = {}

  def register_callback(self, callback, name):
    self.cb_stack[name] = callback     

  def myCallback(self):
    self.register_callback(self.do_things, 'mycb')