On 2:59 PM, Lie Ryan wrote: >> Can any of you guys explain me advantages and disadvantages of >> using each of them > Simplicity is one, using @decor() means you have at least three-level > nested functions, which means the code is likely to be very huge and > perhaps unnecessarily.
Bruce Eckel pointed out ( http://www.artima.com/weblogs/viewpost.jsp?thread=240808) that the result of "decoration" need not be a function. Instead, it can be an object (instance of a user-defined class) that's callable (because the class implements a __call__ method). Investigating how this fact fit in with the current thread, I came up with an alternative to the three levels of "def" (pronounced "three levels of death"). Following is code for two decorators: * the first one encloses the output of a function with lines of "#" characters, and is used like this: @enclose myfun(... * the second one encloses the output of a function with lines of a user-specified character, and is used like this: @enclose("&") myfun(... Here's the Python2 code for each one: ################## decorator to be called with no argument class enclose: """ class that can be used as a function decorator: prints a line of "#" before/after the function's output """ def __init__(self, funarg): self.func = funarg def __call__(self, *args, **kwargs): print "\n" + "#" * 50 self.func(*args, **kwargs) print "#" * 50 + "\n" ################## decorator to be called with argument def enclose(repeat_char): """ function that returns a class that can be used as a decorator: prints a line of <repeat_char> before/after the function's output """ class _class_to_use_as_decorator: def __init__(self, funarg): self.func = funarg def __call__(self, *args, **kwargs): print "\n" + repeat_char * 50 self.func(*args, **kwargs) print repeat_char * 50 + "\n" return _class_to_use_as_decorator Best, John -- http://mail.python.org/mailman/listinfo/python-list
