python学习之面向对象学习进阶
一、property属性高级用法可以将对象方法作为属性使用
例子:
class Foo:
def __init__(self, age):
) self.__age = age
@property
def age(self):
return self.__age
@age.setter
def age(self, args):
self.__age = args
@age.deleter
def age(self):
del self.__age
obj = Foo(20)
print(obj.age)
obj.age = 3
print(obj.age)
del obj.age
print(obj.age)
class Foo:
def __init__(self, age):
self.__age = age
def get_age(self):
return self.__age
def set_age(self, args):
self.__age = args
def del_age(self):
del self.__age
age = property(get_age, set_age, del_age)
obj = Foo(20)
print(obj.age)
obj.age = 3
print(obj.age)
del obj.age
print(obj.age)
__str__方法，默认返回对象内存地址，可以修改重写默认方法
例子:
class Foo:
def __init__(self, name, age):
self.name = name
self.age = age
def __str__(self):
return 'name: %s, age: %s' %(self.name, self.age)
obj = Foo('egon', '18')
print(obj)
__getitem__, __setitem__,__delitem__可以通过字典的方式调用属性和方法
例子:
class Foo:
def __init__(self, name):
self.name = name
def __getitem__(self, item):
print("getitem")
return self.__dict__
def __setitem__(self, key, value):
print("setitem", key, value)
self.__dict__ = value
def __delitem__(self, key):
print('del obj时，执行')
self.__dict__.pop(key)
obj = Foo('egon')
print(obj.name)
#obj.name = 'alex'
#obj['name'] = 'alex'
print(obj['name'])
del obj['name']
print(obj['name'])
__call__回掉函数，可以将对象变成可调用的
例子:
class Foo:
def __call__(self, *args, **kwargs):
print('====>')
obj = Foo()
obj()
__getattr__
从对象中读取某个属性时，首先需要从self.__dicts__中搜索该属性，再从__getattr__中查找
__setattr__用来设置对象的属性，通过object中的__setattr__函数来设置属性
__delattr__用来删除对象的属性
例子:
class Foo:
def __init__(self, x):
self.x = x
def __getattr__(self, item):
print('getattr')
def __setattr__(self, key, value):
self.__dict__ = value
def __delattr__(self, item):
self.__dict__.pop(item)
obj = Foo(10)
obj.x = 1
print(obj.__dict__)
del obj.x
print(obj.__dict__)
obj.a = 1
obj.b = 2
print(obj.__dict__)
del obj.a
print(obj.__dict__)
print(obj.aaaaaaaaa
exec函数，将字符串中的python代码提取出来执行
例子:
s="print(x)"
g={'x':100000000}
l={'x':1}
exec(s,g,l)
s = "y=2"
exec(s, g, l)
print(g)
print(l)
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