重构父类方法和返回值

今天用面向对象写了一段代码,用建立的类重构父类的方法,实现函数锁能实现的功能:代码以下

 1 from os import getpid  2 from time import sleep  3 from multiprocessing import Process  4 
 5 
 6 class MyProcess(Process):  7 
 8     def __init__(self, args):  9         super(MyProcess, self).__init__() 10         self.args = args 11 
12     def run(self): 13         print('Process ID is %s' % getpid()) 14         print('Process %s has been executed ' % self.args) 15 
16     def start(self): 17         print('Process %s will be executed ' % self.args) 18  super().start() 19 
20     def terminate(self): 21  super().terminate() 22 
23     def join(self, timeout=None): 24  super().join() 25 
26     def is_alive(self): 27  super().is_alive() 28 
29 
30 if __name__ == '__main__': 31     process_list = [] 32     for i in range(10): 33         p = MyProcess(i) 34  p.start() 35         print(p.is_alive()) 36  process_list.append(p) 37     for p in process_list: 38         print(p.is_alive()) 39         print('There will terminated process %s' % p) 40  p.terminate() 41         sleep(0.2)      # 这里不延时0.2而直接打印的话,下边的is_alive会显示True
42         print(p.is_alive()) 43  p.join() 44         print(p.is_alive())

重构父类方法

这段代码的执行结果是:

 1 Process 0 will be executed  2 None  3 Process 1 will be executed  4 None  5 Process 2 will be executed  6 None  7 Process 3 will be executed  8 None  9 Process 4 will be executed 10 None 11 Process 5 will be executed 12 None 13 Process 6 will be executed 14 None 15 Process 7 will be executed 16 None 17 Process 8 will be executed 18 None 19 Process 9 will be executed 20 None 21 None 22 There will terminated process <MyProcess(MyProcess-1, started)>
23 None 24 None 25 None 26 There will terminated process <MyProcess(MyProcess-2, started)>
27 Process ID is 14232
28 Process 3 has been executed 29 None 30 None 31 None 32 There will terminated process <MyProcess(MyProcess-3, started)>
33 Process ID is 13276
34 Process 5 has been executed 35 Process ID is 11380
36 Process 4 has been executed 37 None 38 None 39 None 40 There will terminated process <MyProcess(MyProcess-4, stopped)>
41 Process ID is 13616
42 Process 6 has been executed 43 Process ID is 13880
44 Process 7 has been executed 45 Process ID is 9628
46 Process 8 has been executed 47 Process ID is 13052
48 Process 9 has been executed 49 None 50 None 51 None 52 There will terminated process <MyProcess(MyProcess-5, stopped)>
53 None 54 None 55 None 56 There will terminated process <MyProcess(MyProcess-6, stopped)>
57 None 58 None 59 None 60 There will terminated process <MyProcess(MyProcess-7, stopped)>
61 None 62 None 63 None 64 There will terminated process <MyProcess(MyProcess-8, stopped)>
65 None 66 None 67 None 68 There will terminated process <MyProcess(MyProcess-9, stopped)>
69 None 70 None 71 None 72 There will terminated process <MyProcess(MyProcess-10, stopped)>
73 None 74 None

执行结果

发现判断一个进进程是否还在运行后发现打印的全是None,看Process的源码:

 1 def is_alive(self): return False 

发现有返回值.

而本身在这里的想法是直接用super方法调用父类方法后,会执行后返回一个结果,可是这里的使用super()方法后,会是本身重构的方法具备父类的属性,须要一个变量去接,若是须要的话能够返回这个值

若是没有返回值的话,就直接调用父类的方法

修改后的代码以下:

 1 from os import getpid  2 from time import sleep  3 from multiprocessing import Process  4 
 5 
 6 class MyProcess(Process):  7 
 8     def __init__(self, args):  9         super(MyProcess, self).__init__() 10         self.args = args 11 
12     def run(self): 13         print('Process ID is %s' % getpid()) 14         print('Process %s has been executed ' % self.args) 15 
16     def start(self): 17         print('Process %s will be executed ' % self.args) 18  super().start() 19 
20     def terminate(self): 21  super().terminate() 22 
23     def join(self, timeout=None): 24  super().join() 25 
26     def is_alive(self): 27         try: 28             result = super().is_alive() 29             return result 30         except: 31             print("Something was wrong!") 32 
33 
34 if __name__ == '__main__': 35     process_list = [] 36     for i in range(10): 37         p = MyProcess(i) 38  p.start() 39         print(p.is_alive()) 40  process_list.append(p) 41     for p in process_list: 42         print(p.is_alive()) 43         print('There will terminated process %s' % p) 44  p.terminate() 45         sleep(0.2)      # 这里不延时0.2而直接打印的话,下边的is_alive会显示True
46         print(p.is_alive()) 47  p.join() 48         print(p.is_alive())

修改的代码