深入淺出分析Python裝飾器用法

更新時間：2017年07月28日 10:12:31 作者：羅兵

這篇文章主要介紹了Python裝飾器用法,結(jié)合實例形式對比分析了Python裝飾器的定義與使用技巧,需要的朋友可以參考下

本文實例講述了Python裝飾器用法。分享給大家供大家參考，具體如下：

用類作為裝飾器

示例一

最初代碼：

class bol(object):
 def __init__(self, func):
  self.func = func
 def __call__(self):
  return "<b>{}</b>".format(self.func())
class ita(object):
 def __init__(self, func):
  self.func = func
 def __call__(self):
  return "<i>{}</i>".format(self.func())
@bol
@ita
def sayhi():
 return 'hi'

改進一：

class sty(object):
 def __init__(self, tag):
  self.tag = tag
 def __call__(self, f):
  def wraper():
   return "<{tag}>{res}</{tag}>".format(res=f(), tag=self.tag)
  return wraper
@sty('b')
@sty('i')
def sayhi():
 return 'hi'

改進二：

class sty(object):
 def __init__(self, *tags):
  self.tags = tags
 def __call__(self, f):
  def wraper():
   n = len(self.tags)
   return "{0}{1}{2}".format(('<{}>'*n).format(*self.tags), f(), ('</{}>'*n).format(*reversed(self.tags)))
  return wraper
@sty('b', 'i')
def sayhi():
 return 'hi'
print(sayhi())

改進三：

class sty(object):
 def __init__(self, *tags):
  self.tags = tags
 def __call__(self, f):
  def wraper(*args, **kwargs):
   n = len(self.tags)
   return "{0}{1}{2}".format(('<{}>'*n).format(*self.tags), f(*args, **kwargs), ('</{}>'*n).format(*reversed(self.tags)))
  return wraper
@sty('b', 'i')
def say(word='Hi'):
 return word
print(say())
print(say('Hello'))

示例二

最初代碼：

import threading
import time
class DecoratorClass(object):
  def __init__(self):
    self.thread = None
  def __call__(self, func, *args, **kwargs):
    def wrapped_func(*args, **kwargs):
      curr_thread = threading.currentThread().getName()
      self.thread = curr_thread
      print('\nthread name before running func:', self.thread)
      ret_val = func()
      print('\nthread name after running func:', self.thread)
      return ret_val
    return wrapped_func
@DecoratorClass()
def decorated_with_class():
  print('running decorated w class')
  time.sleep(1)
  return
threads = []
for i in range(5):
  t = threading.Thread(target=decorated_with_class)
  threads.append(t)
  t.setDaemon(True)  # 守護
  t.start()

改進：進程鎖

import threading
import time
class DecoratorClass(object):
  def __init__(self):
    self.thread = None
    self.lock = threading.Lock()
  def __call__(self, func, *args, **kwargs):
    def wrapped_func(*args, **kwargs):
      self.lock.acquire()
      curr_thread = threading.currentThread().getName()
      self.thread = curr_thread
      print('thread name before running func:', self.thread)
      ret_val = func()
      print('\nthread name after running func:', self.thread)
      self.lock.release()
      return ret_val
    return wrapped_func
@DecoratorClass()
def decorated_with_class():
  print('Let me sleep 1 second...')
  time.sleep(1)
  return
threads = []
for i in range(5):
  t = threading.Thread(target=decorated_with_class)
  threads.append(t)
  t.start()

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希望本文所述對大家Python程序設(shè)計有所幫助。

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