今日内容
- 嵌套
- 特殊成员:__ init __
- type/isinstance/issubclass/super
- 异常处理
内容回顾
def login():
pass
login()
class Account:
def login(self):
pass
obj = Account()
obj.login()
-
谈谈你了解的面向对象?
-
类和对象是什么关系?对象是类的一个实例。
class Foo: def __ini__(self,name): def run(self): pass obj1 = Foo('alex') obj2 = Foo('eric')
-
self是什么?
#self就是一个形式参数,对象调用方法时,python内部会将该对象传给这个参数 class Foo: def run(self,num): pass boj = Foo() obj.run(5)
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类成员&对象成员 以及他们之间的关系
class Foo: name = 'alex' def run(self): pass obj = Foo()
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类、方法、对象 都可以当作变量或嵌套到其他类型中
class Foo: def run(self): pass v = [Foo,Foo] v = [Foo(),Foo()] obj = Foo() v = [obj.run,obj.run.obj.run]
class School(object): def __init__(self,title): self.title = title def rename(self): pass class Course(object): def __init__(self,name,school_object): self.name = name self.school = school_object def reset_proce(self): pass class Classes(object): def __init__(self,cname,course_object): self.cname = cname self.course_object = course_object def sk(self): pass s1 = School('北京') c1 = Course('Python',s1) c2 = Course('Go',s1) cl1 = Classes('全栈1期',c1)
内容详细
1.嵌套
-
函数:参数可以是任意类型。
-
字典:对象和类都可以做字典的key和value
-
继承的查找关系
class StarkConfig(object): pass class AdminSite(object): def __init__(self): self.data_list = [] def register(self,arg): self.data_list.append(arg) site = AdminSite() obj = StarkConfig() site.register(obj)
class StarkConfig(object): def __init__(self,name,age): self.name = name self.age = age class AdminSite(object): def __init__(self): self.data_list = [] self.sk = None def set_sk(self,arg): self.sk = arg site = AdminSite() #data_list = [] sk = None site.set_sk(StarkConfig) site.sk('alex',19)
class StackConfig(object): pass class Foo(object): pass class Base(object): pass class AdminSite(object): def __init__(self): self._register = {} def registry(self,key,arg): self._register[key] = arg site = AdminSite() site.registry(1,StackConfig) site.registry(2,StackConfig) site.registry(3,StackConfig) site.registry(4,Foo) site.registry(5,Base) for k,v in site._register.items(): print(k,v())
class StackConfig(object): list_display = 'lishaoqi' def changelist_view(self): print(self.list_display) class UserConfig(StackConfig): list_display = 'liqihang' class AdminSite(object): def __init__(self): self._register = {} def registry(self, key, arg=StackConfig): self._register[key] = arg def run(self): for key,value in self._register.items(): obj = value() obj.changelist_view() # print(key,obj.list_display) site = AdminSite() site.registry(1) site.registry(2,StackConfig) site.registry(3,UserConfig) site.run()
2.特殊成员
2.1初始化方法 __ init __
'''
py文件的注释
'''
class Foo:
'''
类是干啥的...
'''
def __init__(self,a1):
'''
初始化方法
:param a1:
'''
self.a1 = a1
obj = Foo('alex')
2.2构造方法 __ new__
class Foo:
def __init__(self):
'''
用于给对象赋值,初始化方法
'''
print('给对象中进行赋值')
self.x = 123
def __new__(cls, *args, **kwargs):
'''
用于创建空对象,构造方法
:param args:
:param kwargs:
'''
print('创建对象')
return object.__new__(cls)
obj = Foo()
print(obj)
2.3 __ cal __
class Foo(object):
def __call__(self, *args, **kwargs):
print('执行call方法')
# obj = Foo()
# obj()
Foo()()
from wsgiref.simple_server import make_server
def func(environ,start_response):
start_response("200 OK",[('Content-Type','text/plain;charset=utf-8')])
return ['你好'.encode('utf-8')]
class Foo(object):
def __call__(self, environ,start_response):
start_response("200 OK", [('Content-Type', 'text/html;charset=utf-8')])
return ['你<h1 style="color:red;">不好</h1>'.encode('utf-8')]
#作用:写一个网站,用户只要来访问,就自动找到第三个参数并执行
server = make_server('127.0.0.1',8000,Foo())
server.serve_forever()
2.4 __ getitem __ __ setitem __ __ delitem __
class Foo(object):
def __setitem__(self, key, value):
print(key,value)
def __getitem__(self, item):
return item + 'uuu'
def __delitem__(self, key):
pass
obj1 = Foo()
obj1['k1'] = 123 #内部会自动调用__setitem__方法
val = obj1['xxx'] #内部会自动调用__getitem__方法
print(val)
del obj1['ttt'] #内部会自动调用__delitem__方法
2.5 __ str __
class Foo(object):
def __str__(self):
'''
只有在打印对象时,会自动化调用此方法,并将其返回值在页面显示出来
:return:
'''
return 'aefsfe'
obj = Foo()
print(obj,type(obj))
class User(object):
def __init__(self,name,email):
self.name = name
self.email = email
def __str__(self):
return '%s %s'%(self.name,self.email)
user_list = [User('二狗','2g@qq.com'),User('二蛋','2d@qq.com'),User('狗蛋','gd@qq.com')]
for item in user_list:
print(item)
2.6 __ dict __
class Foo(object):
def __init__(self,name,age,email):
self.name = name
self.age = age
self.email = email
obj = Foo('alex',19,'xxx@qq.com')
print(obj)
print(obj.name)
print(obj.age)
print(obj.email)
val = obj.__dict__ #去对象中找到所有变量并将其转换为字典
print(val)
2.7上下文管理【面试题】
class Foo(object):
def __enter__(self):
self.x = open('a.txt',mode='a',encoding='utf-8')
return self.x
def __exit__(self, exc_type, exc_val, exc_tb):
self.x.close()
with Foo() as ff:
ff.write('alex')
ff.write('alex')
ff.write('alex')
ff.write('alex')
ff.write('alex')
class Foo(object):
def do_something(self):
print('内部执行')
class Context:
def __enter__(self):
print('进入')
return Foo()
def __exit__(self, exc_type, exc_val, exc_tb):
print('退出')
with Context() as ctx:
print('内部执行')
ctx.do_something()
2.8两个对象相加
val = 5 + 8
print(val)
val = 'alex' + 'sb'
print(val)
class Foo(object):
def __add__(self, other):
return 123
obj1 = Foo()
obj2 = Foo()
val = obj1 + obj2
print(val)
特殊成员:就是为了能够快速实现执行某些方法而生。
3.内置函数补充
3.1 type,查看类型
class Foo:
pass
obj = Foo()
if type(obj) == Foo:
print('obj是Foo类的对象')
3.2 issubclass
class Base:
pass
class Base1(Base):
pass
class Foo(Base1):
pass
class Bar:
pass
print(issubclass(Bar,Base))
print(issubclass(Foo,Base))
3.3 isinstance
# class Base(object):
# pass
# class Foo(Base):
# pass
# class Bar:
# pass
# obj = Foo()
# print(isinstance(obj,Foo)) #判断obj是否是Foo类或基类的实例(对象)
# print(isinstance(obj,Base))
# print(isinstance(obj,Bar))
4. super
class Base(object):
def func(self):
print('base.func')
return 123
class Foo(Base):
def func(self):
v1 = super().func()
print('foo.func',v1)
obj = Foo()
obj.func()
#supper().func()去父类中找func方法并执行
class Bar(object):
def func(self):
print('base.func')
return 123
class Base(Bar):
pass
class Foo(Base):
def func(self):
v1 = super().func()
print('foo.func',v1)
obj = Foo()
obj.func()
#supper().func()根据类的继承关系,按照顺序挨个找func方法并执行(找到第一个就不再往后继续找)
class Base(object): #Base -> object
def func(self):
super().func()
print('base.fun')
class Bar(object):
def func(self):
print('bar.fun')
class Foo(Base,Bar): #Foo -> Base -> Bar
pass
# obj = Foo()
# obj.func()
obj = Base()
obj.func()
#supper().func()根据self对象所属类的继承关系,按照顺序挨个找func方法并执行(找到第一个就不再往后继续找)
5.异常处理
5.1基本格式
try:
pass
except Exception as e:
pass
try:
# int('asdf')
# v = []
# v[10000]
pass
except ValueError as e:
pass
except IndexError as e:
pass
except Exception as e:
print(e) #e是Exception类的对象,中有一个错误信息
# int('asdf') #ValueError
# v = []
# v[10000] #IndexError
try:
# int('asdf')
except Exception as e:
print(e) #e是Exception类的对象,中有一个错误信息
finally:
print('最后无论对错都会执行')
######特殊情况
def func():
try:
#v = 1
#return 123
int('asdf')
except Exception as e:
print(e) #e是Exception类的对象,中有一个错误信息
finally:
print('最后无论对错都会执行')
func()
5.2主动触发异常
try:
int('123')
raise Exception('asfweasd') #代码中主动抛出异常
except Exception as e:
print(e)
def func():
result = False
try:
with open('x.log',mode='r',encoding='utf-8') as f:
data = f.read()
if 'alex' not in data:
raise Exception()
except Exception as e:
result = False
return result
总结
- 特殊成员(**)
- 嵌套
- type/issubclass/isinstance
- super
- 异常