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Re: Decorators not worth the effort

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Terry Reedy於 2012年9月15日星期六UTC+8上午4時40分32秒寫道：
> 2nd try, hit send button by mistake before
> 
> 
> 
> On 9/14/2012 5:28 AM, Jean-Michel Pichavant wrote:
> 
> 
> 
> > Decorators are very popular so I kinda already know that the fault is
> 
> > mine. Now to the reason why I have troubles writing them, I don't
> 
> > know. Every time I did use decorators, I spent way too much time
> 
> > writing it (and debugging it).
> 
> 
> 
> You are writing parameterized decorators, which require inverted 
> 
> currying of the wrapper maker. Perhaps that is why you have trouble. As 
> 
> I showed in response to Cameron, it may be easier to avoid that by using 
> 
> a traditional post-def wrapping call instead of decorator syntax.
> 
> 
>  
> -- 
> 
> Terry Jan Reedy

I'll give another example to show the decorators in python in
versions above 2.4 .

# a general function with the variable input : def  fname( *argc,  **argn)
# a deco is a mapping from an input  funtion to another  function

def deco( fn, *list_in, **dict_in): # use list_in and dict_in to modify fn
    """ deco wrapper """ # deco.__doc__ 

    #print list_in, dict_in, " in the deco"
 
    def wrapper( fn, *argc, **argan): # to be returned as a function
       # do things one wants before calling fn 
       result=fn(*argc, **argn)  # call the original, save the result
       # do things after calling fn   
       return result 
    # enhance the  wrapper and get info of fn
    wrapper.__doc__=fn.__doc__
    # enhance wrapper with result, fn, list_in, dict_in
    #....
     return wrapper

def f1():
   """ doc of f1"""
   print "inside f1"

f2=deco(f1, 2,3,4,5,6, MSG="deco f1 to f2")

f2() # invoke the decorated function from f1


# For a deco maps a deco to another deco  can be done similarly

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Re: Python presentations Jean-Michel Pichavant <jeanmichel@sequans.com> - 2012-09-13 19:54 +0200
  Re: Python presentations Alister <alister.ware@ntlworld.com> - 2012-09-13 18:18 +0000
  Decorators not worth the effort alex23 <wuwei23@gmail.com> - 2012-09-13 18:58 -0700
    Re: Decorators not worth the effort Cameron Simpson <cs@zip.com.au> - 2012-09-14 12:12 +1000
      Re: Decorators not worth the effort alex23 <wuwei23@gmail.com> - 2012-09-13 20:25 -0700
    Re: Decorators not worth the effort Dieter Maurer <dieter@handshake.de> - 2012-09-14 08:40 +0200
    Re: Decorators not worth the effort Terry Reedy <tjreedy@udel.edu> - 2012-09-14 16:29 -0400
      Re: Decorators not worth the effort Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2012-09-15 09:13 +0200
      Re: Decorators not worth the effort alex23 <wuwei23@gmail.com> - 2012-09-16 17:38 -0700
    Re: Decorators not worth the effort Terry Reedy <tjreedy@udel.edu> - 2012-09-14 16:31 -0400
    Re: Decorators not worth the effort Terry Reedy <tjreedy@udel.edu> - 2012-09-14 16:37 -0400
      Re: Decorators not worth the effort 88888 Dihedral <dihedral88888@googlemail.com> - 2012-09-18 16:47 -0700
      Re: Decorators not worth the effort 88888 Dihedral <dihedral88888@googlemail.com> - 2012-09-18 16:47 -0700
    Re: Decorators not worth the effort Terry Reedy <tjreedy@udel.edu> - 2012-09-14 16:33 -0400
    Re: Decorators not worth the effort Ian Kelly <ian.g.kelly@gmail.com> - 2012-09-14 15:16 -0600
      Re: Decorators not worth the effort Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-09-14 23:39 +0000
        Re: Decorators not worth the effort 88888 Dihedral <dihedral88888@googlemail.com> - 2012-09-15 02:45 -0700
          Re: Decorators not worth the effort Dwight Hutto <dwightdhutto@gmail.com> - 2012-09-15 06:04 -0400
            Re: Decorators not worth the effort 88888 Dihedral <dihedral88888@googlemail.com> - 2012-09-15 07:18 -0700
              Re: Decorators not worth the effort Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2012-09-18 14:16 +0200
            Re: Decorators not worth the effort 88888 Dihedral <dihedral88888@googlemail.com> - 2012-09-15 07:18 -0700
    Re: Decorators not worth the effort Dwight Hutto <dwightdhutto@gmail.com> - 2012-09-14 23:42 -0400
    Re: Decorators not worth the effort "Dieter Maurer" <dieter@handshake.de> - 2012-09-15 08:31 +0200

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