14、Python之反射

一、反射

   反射的本质是：通过知道对象属性或方法的字符串形式，就能够访问该对象的属性和方法的过程。

1、检查对象是否有某个属性或方法，使用hasattr。

 1 class Dog(object):
 2     def __init__(self,name):
 3         self._name = name
 4     def bark(self):
 5         print("%s is barking" % self._name)
 6 
 7 d = Dog("lido")
 8 print(hasattr(d,"bark")) #True -  有bark方法
 9 print(hasattr(d,"bark1"))#False - 无bark1方法
10 print(hasattr(d,"_name"))#True  -  有_name属性

 

2、通过属性或方法的字符串形式获得属性的值或方法的地址，使用getattr。

 1 class Dog(object):
 2     def __init__(self,name):
 3         self._name = name
 4     def bark(self):
 5         print("%s is barking" % self._name)
 6 
 7 d = Dog("lido")
 8 bark_address = getattr(d,"bark")#通过bark的字符串返回其地址
 9 bark_address()
10 name_01 = getattr(d,"_name")
11 print(name_01)

3、给对象动态添加属性或者方法，使用setattr

 1 def run(name):
 2     print("%s is running" % name)
 3 
 4 class Dog(object):
 5     def __init__(self,name):
 6         self._name = name
 7     def bark(self):
 8         print("%s is barking" % self._name)
 9 
10 d = Dog("lido")
11 setattr(d,"_age",20)
12 setattr(d, 'run',run)
13 print(d._age)
14 d.run(d._name)

4、动态删除对象的属性或者方法，使用delattr。

 1 class Dog(object):
 2     def __init__(self,name):
 3         self._name = name
 4     def bark(self):
 5         print("%s is barking" % self._name)
 6 
 7 d = Dog("lido")
 8 delattr(d,"bark")
 9 delattr(d,"_name")
10 d.bark()
11 print(d._name)

5、如果只知道一个类的字符串形式，如何来创建类对象呢，方法有很多这里暂时先介绍一种，使用globals方法，这个方法返回一个字典，以类名的字符串作为key，地址作为value。代码如下：

1 class Dog(object):
2     def __init__(self,name):
3         self._name = name
4     def bark(self):
5         print("%s is barking" % self._name)
6 
7 D = globals()["Dog"]
8 d = D("go")
9 d.bark()

6、综合实例

 1 class Dog(object):
 2     def __init__(self):
 3         # self._name = name
 4         pass
 5     def bark(self):
 6         print("%s is barking" % self._name)
 7     def run(self):
 8         print("%s is running" % self._name)
 9     def sleep(self):
10         print("%s is sleeping" % self._name)
11     def print_self(self):
12         print("my name is %s" % self._name)
13 d = Dog()
14 setattr(d,"_name",input("请输入狗的姓名>>"))
15 while True:
16     choice = input("1、bark,1、run,3、sleep,4、print_selft")
17     if choice == '1':
18         break
19     if hasattr(d,choice):
20         getattr(d,choice)()
21     else:
22         print("输入错误")
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posted @ 2018-03-01 16:25  高文祥888888  阅读(152)  评论(0)  编辑  收藏  举报