本文实例讲述了Python抽象和自定义类定义与用法。分享给大家供大家参考，具体如下：
抽象方法
|
1
2
3
4
5
6
|
class Person():
def say(self):
pass
class Student(Person):
def say(self):
print("i am student")
|
抽象类： 包含抽象方法的类
- 抽象类可以包含非抽象方法
- 抽象类可以有方法和属性
- 抽象类不能进行实例化
- 必须继承才能使用，且继承的子类必须实现所有抽象方法
|
1
2
3
4
5
6
7
8
9
10
|
import abc
class Person(metaclass=abc.ABCMeta):
@abc.abstractmethod
def say(self):
pass
class Student(Person):
def say(self):
print("i am student")
s = Student()
s.say()
|
补充：函数名和当做变量使用
|
1
2
3
4
5
6
7
|
class Student():
pass
def say(self):
print("i am say")
s = Student()
s.say=say
s.say(9)
|
组装类
|
1
2
3
4
5
6
7
8
|
from types import MethodType
class Student():
pass
def say(self):
print("i am say")
s = Student()
s.say=MethodType(say,Student)
s.say()
|
元类
|
1
2
3
4
5
6
7
8
9
|
# 类名一般为MetaClass结尾
class StudentMetaClass(type):
def __new__(cls, *args, **kwargs):
print("元类")
return type.__new__(cls, *args, **kwargs)
class Teacher(object, metaclass=StudentMetaClass):
pass
t = Teacher()
print(t.__dict__)
|
附：python 抽象类、抽象方法的实现示例
由于python 没有抽象类、接口的概念，所以要实现这种功能得abc.py 这个类库,具体方式如下
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
from abc import ABCMeta, abstractmethod
#抽象类
class Headers(object):
__metaclass__ = ABCMeta
def __init__(self):
self.headers = ''
@abstractmethod
def _getBaiduHeaders(self):pass
def __str__(self):
return str(self.headers)
def __repr__(self):
return repr(self.headers)
#实现类
class BaiduHeaders(Headers):
def __init__(self, url, username, password):
self.url = url
self.headers = self._getBaiduHeaders(username, password)
def _getBaiduHeaders(self, username, password):
client = GLOBAL_SUDS_CLIENT.Client(self.url)
headers = client.factory.create('ns0:AuthHeader')
headers.username = username
headers.password = password
headers.token = _baidu_headers['token']
return headers
|
如果子类不实现父类的_getBaiduHeaders方法,则抛出TypeError: Can't instantiate abstract class BaiduHeaders with abstract methods 异常
希望本文所述对大家Python程序设计有所帮助。
原文链接：https://blog.csdn.net/smj20170417/article/details/81133911