class
foo():
def__init__
(self):
print("foo-init")
def__call__
(self):
print("foo-call")
f = foo()
f() # 過載了括號運算子
"""foo-init
foo-call
"""
class
decorator
():def
__init__
(self, func):
print("decorator-init")
self.fun = func
def__call__
(self, args1, args2):
print("decorator-call")
self.fun(args1, args2)
@decorator
defadd
(a, b):
print("a+b:", a+b)
# add(1, 2)
"""decorator-init
decorator-call
a+b: 3
"""
class
mytuple
(tuple):
def__init__
(self, seq):
print("mytuple-init")
print("self:", self)
# takes no parameters
super(mytuple, self).__init__()
def__new__
(cls, seq):
print("mytuple-new")
# 過濾
g = [i for i in seq if isinstance(i ,int)]
# 返回物件：self
return super(mytuple, cls).__new__(cls, g)
t = mytuple([1, 2, "-1"])
print(type(t), t)
"""mytuple-new
mytuple-init
self: (1, 2)
(1, 2)
"""
# 描述符 : 允許你自定義在引用乙個物件屬性時應該完成的事情
# __set__:在設計屬性的時候被呼叫
# __get__:在讀取屬性的時候被呼叫
# __delete__:在刪除屬性的時候被呼叫
class
descriptor
():def
__get__
(self, instance, owner):
print("get")
def__set__
(self, instance, value):
print("set")
def__delete__
(self, instance):
print("delete")
class
a():
x = descriptor()
a = a()
a.xa.x = 1
del a.x
"""get
setdelete
"""
class
attr
():def
__init__
(self, name, name_type):
self.name = name
self.name_type = name_type
def__get__
(self, instance, owner):
return instance.__dict__[self.name]
def__set__
(self, instance, value):
ifnot isinstance(value, self.name_type):
raise typeerror("expected an {}".format(self.name_type))
instance.__dict__[self.name] = value
def__delete__
(self, instance):
del instance.__dict__[self.name]
# p.name='jack' #名字必須是str
# p.age=18 #年齡必須是int
class
person
(): name = attr("name", str)
age = attr("age", int)
p=person()
p.name= "tom"
p.age = 123
參考：面試python如果你說出這幾招，讓你瞬間牛叉
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