#不带参数的装饰器
@dec1
@dec2
def func():
  ...
#这个函数声明等价于
func = dec1(dec2(func))
#带参数的装饰器
@dec(some_args)
def func():
  ...
#这个函数声明等价于
func = dec(some_args)(func)

def decorator(func):
  def decorator_func()
    func()
  return decorated_func

> def decorator(func):
...   def decorated_func():
...     func(1)
...   return decorated_func
... 
#声明时就被调用
> @decorator
... def func(x):
...   print x
... 
decorator being called 
#使用func()函数实际上使用的是decorated_func函数
> func()
1
> func.__name__
'decorated_func'

#@wraps(func)的操作相当于
#在return decorated_func之前，执行
#decorated_func.__name__ = func.__name__
#func作为装饰器参数传入， 
#decorated_func则作为wraps返回的函数的参数传入
> def decorator(func):
...   @wraps(func)
...   def decorated_func():
...     func(1)
...   return decorated_func
... 
#声明时就被调用
> @decorator
... def func(x):
...   print x
... 
decorator being called 
#使用func()函数实际上使用的是decorated_func函数
> func()
1
> func.__name__
'func'

#!/usr/bin/env python
#filename decorator.py
def decorator(func):
  #注意这里使用可变对象
  a = [0]
  def decorated_func(*args,**keyargs):
    func(*args, **keyargs)
    #因为闭包是浅拷贝，如果是不可变对象，每次调用完成后符号都会被清空，导致错误
    a[0] += 1
    print "%s have bing called %d times" % (func.__name__, a[0])
  return decorated_func
@decorator
def func(x):
  print x
@decorator
def theOtherFunc(x):
  print x

#coding=UTF-8
#!/usr/bin/env python
#filename decorator.py
import time
from functools import wraps
def decorator(func):
  "cache for function result, which is immutable with fixed arguments"
  print "initial cache for %s" % func.__name__
  cache = {}
  @wraps(func)
  def decorated_func(*args,**kwargs):
    # 函数的名称作为key
    key = func.__name__
    result = None
    #判断是否存在缓存
    if key in cache.keys():
      (result, updateTime) = cache[key]
      #过期时间固定为10秒
      if time.time() -updateTime < 10:
        print "limit call 10s", key
        result = updateTime
      else :
        print "cache expired !!! can call "
        result = None
    else:
      print "no cache for ", key
    #如果过期，或则没有缓存调用方法
    if result is None:
      result = func(*args, **kwargs)
      cache[key] = (result, time.time())
    return result
  return decorated_func
@decorator
def func(x):
  print 'call func'

> from decorator import func
initial cache for func
> func(1)
no cache for func
call func
> func(1)
limit call 10s func
1488082913.239092
> func(1)
cache expired !!! can call
call func
> func(1)
limit call 10s func
1488082923.298204
> func(1)
cache expired !!! can call
call func
> func(1)
limit call 10s func
1488082935.165979
> func(1)
limit call 10s func
1488082935.165979