python中的匿名函数及编写无参数decorator详解

>>> map(lambda x: x * x, [1, 2, 3, 4, 5, 6, 7, 8, 9])
[1, 4, 9, 16, 25, 36, 49, 64, 81]

def f(x):
    return x * x

>>> sorted([1, 3, 9, 5, 0], lambda x,y: -cmp(x,y))
[9, 5, 3, 1, 0]

>>> myabs = lambda x: -x if x < 0 else x 
>>> myabs(-1)
1
>>> myabs(1)
1

def is_not_empty(s):
    return s and len(s.strip()) > 0
filter(is_not_empty, ['test', None, '', 'str', '  ', 'END'])

print filter(lambda s: s and len(s.strip())>0, ['test', None, '', 'str', '  ', 'END'])

def log(f):
    def fn(x):
        print 'call ' + f.__name__ + '()...'
        return f(x)
    return fn

@log
def factorial(n):
    return reduce(lambda x,y: x*y, range(1, n+1))
print factorial(10)

@log
def add(x, y):
    return x + y
print add(1, 2)

def log(f):
    def fn(*args, **kw):
        print 'call ' + f.__name__ + '()...'
        return f(*args, **kw)
    return fn

import time
def performance(f):
    def fn(*args, **kw):
        t1 = time.time()
        r = f(*args, **kw)
        t2 = time.time()
        print 'call %s() in %fs' % (f.__name__, (t2 - t1))
        return r
    return fn
@performance
def factorial(n):
    return reduce(lambda x,y: x*y, range(1, n+1))
print factorial(10)