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Great Python Decorator Example

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  1. def decorator_maker_with_arguments(decorator_arg1, decorator_arg2) :
  2.  
  3.     print "I make decorators ! And I accept arguments:", decorator_arg1, decorator_arg2
  4.  
  5.     def my_decorator(func) :
  6.         # The hability to pass arguments here is a gift from closures.
  7.         # If you are not confortable with closures, you can assume it's ok,
  8.         # or read : http://stackoverflow.com/questions/13857/can-you-explain-closures-as-they-relate-to-python
  9.         print "I am the decorator. Somehow you passed me arguments:", decorator_arg1, decorator_arg2
  10.  
  11.         # Don't confuse decorator arguments and function arguments !
  12.         def wrapped(function_arg1, function_arg2) :
  13.             print "I am the wrapper arround the decorated function.",\
  14.                   "\nI can access all the variables",\
  15.                   "\n\t- from the decorator:", decorator_arg1, decorator_arg2,\
  16.                   "\n\t- from the function call:", function_arg1, function_arg2,\
  17.                   "\nThen I can pass them to the decorated function"
  18.             return func(function_arg1, function_arg2)
  19.  
  20.         return wrapped
  21.  
  22.     return my_decorator
  23.  
  24. @decorator_maker_with_arguments("Leonard", "Sheldon")
  25. def decorated_function_with_arguments(function_arg1, function_arg2) :
  26.     print "I am the decorated function and only knows about my arguments :",\
  27.           function_arg1, function_arg2
  28.  
  29. decorated_function_with_arguments("Rajesh", "Howard")
  30. #outputs:
  31. #I make decorators ! And I accept arguments: Leonard Sheldon
  32. #I am the decorator. Somehow you passed me arguments: Leonard Sheldon
  33. #I am the wrapper arround the decorated function. 
  34. #I can access all the variables 
  35. #   - from the decorator: Leonard Sheldon 
  36. #   - from the function call: Rajesh Howard 
  37. #Then I can pass them to the decorated function
  38. #I am the decorated function and only knows about my arguments : Rajesh Howard

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