Dynamically add decorators into python functions

dynamic_decorator.py

# -*- coding: utf-8 -*-
"""
$ python dynamic_decorator.py

func_to_be_dynamically_decorated(1, 2)
3
unreg = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_1)
<function unreg at 0x7f5260d1f9b0>
func_to_be_dynamically_decorated(1, 2)
4
unreg()
True
func_to_be_dynamically_decorated(1, 2)
3
======================================================================
func_to_be_dynamically_decorated(1, 2)
3
unreg = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_2)
<function unreg at 0x7f5260d1fa28>
func_to_be_dynamically_decorated(1, 2)
27
unreg()
True
func_to_be_dynamically_decorated(1, 2)
3
======================================================================
func_to_be_dynamically_decorated(1, 2)
3
unreg1 = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_1)
<function unreg at 0x7f5260d1f9b0>
unreg2 = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_2)
<function unreg at 0x7f5260d1faa0>
func_to_be_dynamically_decorated(1, 2)
256
unreg1()
True
func_to_be_dynamically_decorated(1, 2)
27
unreg2()
True
func_to_be_dynamically_decorated(1, 2)
3
======================================================================
func_to_be_dynamically_decorated(1, 2)
3
unreg1 = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_2)
<function unreg at 0x7f5260d1fb90>
unreg2 = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_1)
<function unreg at 0x7f5260d1f9b0>
func_to_be_dynamically_decorated(1, 2)
28
unreg1()
True
func_to_be_dynamically_decorated(1, 2)
4
unreg2()
True
func_to_be_dynamically_decorated(1, 2)
3

"""

DYNAMIC_DECORATORS = {}


def add_dynamic_decorator(fname, dynamic_decorator):
  def unreg():
    if not fname in DYNAMIC_DECORATORS:
      return False

    if not dynamic_decorator in DYNAMIC_DECORATORS[fname]:
      return False

    cb_idx = DYNAMIC_DECORATORS[fname].index(dynamic_decorator)
    DYNAMIC_DECORATORS[fname] = DYNAMIC_DECORATORS[fname][:cb_idx] + DYNAMIC_DECORATORS[fname][cb_idx + 1:]

    return True

  if fname not in DYNAMIC_DECORATORS:
    DYNAMIC_DECORATORS[fname] = []

  DYNAMIC_DECORATORS[fname].append(dynamic_decorator)

  return unreg



def _accepts_dynamic_decorator(func):
  def wrap(*args, **kwds):
    if func.__name__ not in DYNAMIC_DECORATORS:
      return func(*args, **kwds)

    func_wrap = func

    for dyn_deco in DYNAMIC_DECORATORS[func.__name__]:
      func_wrap = dyn_deco(func_wrap)

    return func_wrap(*args, **kwds)

  return wrap



@_accepts_dynamic_decorator
def func_to_be_dynamically_decorated(arg1, arg2):
  return arg1 + arg2



def dynamic_decorator_1(func):
  def wrap(*args, **kwds):
    return 1 + func(*args, **kwds)
  return wrap



def dynamic_decorator_2(func):
  def wrap(*args, **kwds):
    r = func(*args, **kwds)
    return r ** r
  return wrap



def main():
  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  print('unreg = add_dynamic_decorator(\'func_to_be_dynamically_decorated\', dynamic_decorator_1)')
  unreg = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_1)
  print(unreg)

  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  print('unreg()')
  print(unreg())

  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  # ===================================================================
  print('=' * 70)
  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  print('unreg = add_dynamic_decorator(\'func_to_be_dynamically_decorated\', dynamic_decorator_2)')
  unreg = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_2)
  print(unreg)

  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  print('unreg()')
  print(unreg())

  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  # ===================================================================
  print('=' * 70)
  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  print('unreg1 = add_dynamic_decorator(\'func_to_be_dynamically_decorated\', dynamic_decorator_1)')
  unreg1 = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_1)
  print(unreg1)

  print('unreg2 = add_dynamic_decorator(\'func_to_be_dynamically_decorated\', dynamic_decorator_2)')
  unreg2 = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_2)
  print(unreg2)

  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  print('unreg1()')
  print(unreg1())

  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  print('unreg2()')
  print(unreg2())

  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  # ===================================================================
  print('=' * 70)
  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  print('unreg1 = add_dynamic_decorator(\'func_to_be_dynamically_decorated\', dynamic_decorator_2)')
  unreg1 = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_2)
  print(unreg1)

  print('unreg2 = add_dynamic_decorator(\'func_to_be_dynamically_decorated\', dynamic_decorator_1)')
  unreg2 = add_dynamic_decorator('func_to_be_dynamically_decorated', dynamic_decorator_1)
  print(unreg2)

  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  print('unreg1()')
  print(unreg1())

  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))

  print('unreg2()')
  print(unreg2())

  print('func_to_be_dynamically_decorated(1, 2)')
  print(func_to_be_dynamically_decorated(1, 2))



if __name__ == '__main__':
  main()