#isinstance(obj,cls)判断obj是否是类cls的实例

#issubclass(cls,cls1)判断cls是否是cls1的子类或派生类

class Foo:

    pass

class Bar(Foo):

    pass

print(issubclass(Bar,Foo))#检查sub类是否是super类的派生类

f1=Foo()

print(isinstance(f1,Foo))#检查是否obj是否是类cls对象

#自定义格式化的format方法

x='{0}{0}{0}'.format("dog")

print(x)

format_dic={

    'ymd':"{0.year}{0.mon}{0.day}",

    "m-d-y":"{0.mon}-{0.day}-{0.year}",

    "y:m:d":"{0.year}:{0.mon}:{0.day}"

}

class Date:

    def __init__(self,year,mon,day):

        self.year=year

        self.mon=mon

        self.day=day

    def __format__(self, format_spec):#改写系统内置的format属性

        print("我执行了")

        print("-->",format_spec)

        if format_spec:

            fm=format_dic[format_spec]

            return fm.format(d1)

        else:

            return "为空"

d1=Date(2016,12,26)

#format(d1)#d1.__format__()

print(format(d1))#d1.__format__()

print(format(d1,"ymd"))

d1.name="alex"

print(d1.name)

# x='{0.year}{0.mon}{0.day}'.format(d1)

# print(x)

###改变字符串的显示方法 str,repr

# l=list("hello")

#

# print(l)

# class Foo:

#     def __str__(self):

#         return "自己定制的对象的显示方式"

#

# f1=Foo()

# print(f1)#-->str(f1)-->f1.__str__()

# file=open("test.txt","w")

# print(file)

#自己定制str方法

class Foo:

    def __init__(self,name,age):

        self.name=name

        self.age=age

    # def __str__(self):#当前str与repr共存

    #     return "这是str"

    #

    # def __repr__(self):#repr或者交互式解释器

    #     return "名字是%s 年龄是%s" %(self.name,self.age)

f1=Foo("egon",19)

#repr(f1)-->f1.__repr__()

# print(f1)#str(f1)--->f1.__str__()----->f1.__repr__()

f1.__str__()

print(str(f1))

#call方法,对象通过()访问

class Foo:

    def __call__(self, *args, **kwargs):

        print("实例执行了obj")

f1=Foo()

f1()#foo下的.__call__

Foo()#abc下的__call__

#通过类的next和iter实现迭代器协议

class Foo:

    def __init__(self,n):

        self.n=n

    def __iter__(self):

        return self

    def __next__(self):

         if self.n==100:

             raise StopIteration("终止了")

         self.n+=1

         return self.n

# l=list('hello')

# for i in l:

#     print(i)

f1=Foo(10)

print(next(f1))

print(next(f1))

print(f1.__next__())

for i in f1: #f1.__iter__() ==iter(f1)

    print(i)#next(f1) for循环捕捉异常终止

class Fib:

    def __init__(self):
        self.a=1
        self.b=1

    def __iter__(self):
        return self

    def __next__(self):
        self.a,self.b=self.b, self.a+self.b
        if self.b>100:
            raise StopIteration("终止了")
        return self.a

f1=Fib()
print(next(f1))
print(next(f1))
print(next(f1))
print(next(f1))
print(next(f1))
print(next(f1))
print(next(f1))
print(next(f1))
print("=====>")
for i in f1:
    print(i)

class Foo:

    # __slots__ = ["name","age"]#{"name":none,"age":"none"}

    __slots__ = "name"#限定实例的数据属性,节省内存

f1=Foo()

f1.name="egon"

print(f1.name)

#f1.age=18 #__setattr__---->f1.__dict__["age"]=18

# print(f1.__dict__)

print(f1.__slots__)

print(f1.__slots__)