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(Other hooks could be similarly added) (Other hooks could be similarly added. Exceptions are left out for simplicity
of demonstration.
)
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WHAT_TO_DEBUG = sets.Set(['io', 'core']) WHAT_TO_DEBUG = sets.Set(['io', 'core'])  # change to what you need
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    """ Decorator which helps to control what aspects of a program to debug
    on per-function basis. Aspects are provided as list of arguments.
    It DOESN'T slowdown functions which aren't supposed to be debugged.
    """

This page is meant to be a central repository of decorator code pieces, whether useful or not <wink>. It is NOT a page to discuss decorator syntax!

Feel free to add your suggestions (please use the current decorator syntax @dec)!

Memoize

Here's a memoizing class.

inline:memoize.py

Pseudo-currying

   1 class curried(object):
   2   """
   3   Decorator that returns a function that keeps returning functions
   4   until all arguments are supplied; then the original function is
   5   evaluated.
   6   """
   7 
   8   def __init__(self, func, *a):
   9     self.func = func
  10     self.args = a
  11   def __call__(self, *a):
  12     args = self.args + a
  13     if len(args) < self.func.func_code.co_argcount:
  14       return curried(self.func, *args)
  15     else:
  16       return self.func(*args)
  17 
  18 
  19 @curried
  20 def add(a, b):
  21     return a+b
  22 
  23 add1 = add(1)
  24 
  25 print add1(2)

Controllable DIY debug

(Other hooks could be similarly added. Exceptions are left out for simplicity of demonstration.)

   1 import sys, sets
   2 
   3 WHAT_TO_DEBUG = sets.Set(['io', 'core'])  # change to what you need
   4 
   5 class deBug:
   6     """ Decorator which helps to control what aspects of a program to debug
   7     on per-function basis. Aspects are provided as list of arguments. 
   8     It DOESN'T slowdown functions which aren't supposed to be debugged.
   9     """
  10     def __init__(self, aspects=None):
  11         self.aspects = sets.Set(aspects)
  12 
  13     def __call__(self, f):
  14         if self.aspects & WHAT_TO_DEBUG:
  15             def newf(*args, **kwds):
  16                 print >> sys.stderr, f.func_name, args, kwds
  17                 f_result = f(*args, **kwds)
  18                 print >> sys.stderr, f.func_name, "returned", f_result
  19                 return f_result
  20             return newf
  21         else:
  22             return f
  23 
  24 @deBug(['io'])
  25 def prn(x):
  26     print x
  27 
  28 @deBug(['core'])
  29 def mult(x, y):
  30     return x * y
  31 
  32 prn(mult(2,2))

PythonDecoratorLibrary (last edited 2017-07-04 09:44:35 by mjpieters)

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