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@psachin
Last active Aug 29, 2015
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#/usr/bin/env python
# ex1.py
@g
def f():
print("xyz")
# is equivalent to
def f():
print("xyz")
f = g(f)
# -----
# ex2.py
# Example of decorator
def gg(xx):
print "gg called"
def s(y):
return y-1
return s
@gg
def ff(x):
print "ff called"
return x+1
print ff(3)
# -----
# ex3.py
# Check/Modify input argument
def gg(func):
"""A decorator for ff. Make sure input to ff is always even, else, add
1 to make it even."""
def hh(y):
if y % 2 ==0:
return func(y)
else:
return func(y+1)
return hh
@gg
def ff(x):
return x
print ff(3)
print ff(2)
print ff(9)
# -----
# ex4.py
# Example of decorator that check condition to decide whether to call
cc = True # change this to False to toggle
# decorator action.
def gg(func): # decorator
"""a decorator for ff. If cc is true, run ff, else do nothing."""
def hh(*args, **kwargs): # params must catch all args of ff
"""do nothing function"""
pass
if cc:
return func
else:
return hh
@gg
def ff(*args, **kwargs):
# ff can be sending email, or any callable with no return value
print "ff"
pass
ff()
ff(3)
ff(3, "jane")
ff(3,4,k="thankyou")
# -----
# ex5.py
# Decorator with parameter
'''
@g(3)
def f():
print("xyz")
is equivaqlent to
def f():
print("xyz")
f = g(3)(f)
'''
def gg(num):
"""a decorator for ff. Ignore ff. Simply return num."""
def h1(f1):
def h2(f2):
return num
return h2
return h1
# gg(1) must return a function h1, such that h1 accept function (the
# ff), and also return a function (to be applied to ff's args))
@gg(1)
def ff(x):
return repr(x) + " rabbits"
print ff(3)
print ff(4)
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