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 help to control what aspects to debug.
7 Aspects are provided as list of arguments. It DOESN'T
8 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))