Python3入门笔记七之面向对象高级编程

class Student(object):
    __slots__ = ('name', 'age') # 用tuple定义允许绑定的属性名称
s = Student()
s.name='a'
s.age=11
s.score=99 # AttributeError: 'Student' object has no attribute 'score'
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class Student(object):
    @property
    def score(self):
        return self._score
    @score.setter
    def score(self, value):
        if not isinstance(value, int):
            raise ValueError('score must be an integer!')
        if value < 0 or value > 100:
            raise ValueError('score must between 0 ~ 100!')
        self._score = value
s = Student()
s.score=11
s.score
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class Dog(Mammal, RunnableMixIn):
    pass
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class MyUDPServer(UDPServer, ThreadingMixIn):
    pass
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class Student(object):
    def __init__(self, name):
        self.name = name
    def __str__(self): # 2
        return 'Student object (name=%s)' % self.name
    __repr__ = __str__ # 1
s=Student('ken')
s # 2
print(s) # 1 Student object (name=ken)
# 同时注释掉 # 1 的内容就可以看到效果
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class Fib(object):
    def __init__(self):
        self.a, self.b = 0, 1 # 初始化两个计数器a，b
    def __iter__(self):
        return self # 实例本身就是迭代对象，故返回自己
    def __next__(self):
        self.a, self.b = self.b, self.a + self.b # 计算下一个值
        if self.a > 100: # 退出循环的条件
            raise StopIteration()
        return self.a # 返回下一个值
for n in Fib():
    print(n) # 1 1 2 3 5 8...89
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class Fib(object):
    def __getitem__(self, n):
        a, b = 1, 1
        for x in range(n):
            a, b = b, a + b
        return a
f = Fib()
f[10] # 89
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class Fib(object):
    def __getitem__(self, n):
        if isinstance(n, int): # n是索引
            a, b = 1, 1
            for x in range(n):
                a, b = b, a + b
            return a
        if isinstance(n, slice): # n是切片
            start = n.start
            stop = n.stop
            step = n.step
            print('step:',step)
            if start is None:
                start = 0
            if step is None:
                step = 1
            a, b = 1, 1
            L = []
            for x in range(stop):
                if x >= start:
                    if(x%step==0):
                        L.append(a)
                a, b = b, a + b
            return L
f=Fib()
print(f[:10]) #  [1, 1, 2, 3, 5, 8, 13, 21, 34, 55] 
print(f[:10:2]) # [1, 2, 5, 13, 34]
print(f[10]) # 89
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class Student(object):
    def __init__(self, name):
        self.name = name
    def __call__(self):
        print('My name is %s.' % self.name)
s = Student('Michael')
if callable(s):
    s() # My name is Michael.
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class Student(object):
    def __getattr__(self, attr):
        if attr=='age':
            return lambda: 25
        elif attr =='name':
            return 'Amy'
s = Student()
print(s.age()) # 25 注意这里返回的是一个lambda表达式，需要调用该方法才能拿到值
print(s.name) # Amy 
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class Chain(object):
    def __init__(self, path=''):
        self._path = path
    def __getattr__(self, path):
        return Chain('%s/%s' % (self._path, path))
    def __call__(self, path):
        return Chain('%s/%s' % (self._path, path))
    def __str__(self):
        return self._path
    __repr__ = __str__
print(Chain().status.user.timeline.list) # /status/user/timeline/list
# 注意这里的chain返回的是chain对象，所以这个users('michael')就可以很好地理解了。
print(Chain().users('michael').repos) # /users/michael/repos
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from enum import Enum
Month = Enum('Month', ('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'))
for name, member in Month.__members__.items():
    print(name, '=>', member, ',', member.value)
# value属性则是自动赋给成员的int常量，默认从1开始计数。
# Jan => Month.Jan , 1
# Feb => Month.Feb , 2
# Mar => Month.Mar , 3
# .
# .
# .
# Dec => Month.Dec , 12
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from enum import Enum, unique
@unique # @unique装饰器可以帮助我们检查保证没有重复值。
class Weekday(Enum):
    Sun = 0 # Sun的value被设定为0
    Mon = 1
    Tue = 2
    Wed = 3
    Thu = 4
    Fri = 5
    Sat = 6
print(Weekday.Mon,'=',Weekday.Mon.value) # Weekday.Mon = 1
print(Weekday['Mon'],'=',Weekday.Mon.value)  # Weekday.Mon = 1
print(Weekday(1),'=',Weekday.Mon.value)  # Weekday.Mon = 1
for name, member in Weekday.__members__.items():
    print(name, '=>', member)
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class Gender(Enum):
    Male = 0
    Female = 1
class Student(object):
    def __init__(self, name, gender):
        self.name = name
        self.gender = gender
    def __str__(self):
          return 'Student object name={},gender={}'.format(self.name,self.gender)
    __repr__=__str__
bart = Student('Bart', Gender.Male)
print(bart) #  Student object name=Bart,gender=Gender.Male
bart # Student object name=Bart,gender=Gender.Male
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print(type(str)) # <class 'type'>  str是class，所以类型是type
print(type('123')) # <class 'str'> '123'是实例。所以类型是str
def fn(self, name='world'): # 先定义函数    
    print('Hello, %s.' % name)
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def fn(self, name='world'):
    return name
Hello=type('Hello',(object,),dict(hello=fn)) # 创建出Hello类
h=Hello() # 注意这里才去创建Instance实例
print(h.hello('1'))
print(type(Hello)) # <class 'type'>
print(type(h)) # <class '__main__.Hello'>
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# metaclass是类的模板，所以必须从`type`类型派生：
class ListMetaclass(type):
    def __new__(cls, name, bases, attrs):
        attrs['add'] = lambda self, value: self.append(value)
        return type.__new__(cls, name, bases, attrs)
class MyList(list, metaclass=ListMetaclass):
    pass
L = MyList()
L.add(1)
L # 1
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