Item 28: Bound Method

class EventSource(object):
    def __init__(self):
        self._callbacks = []
    def register(self, callback):
        print('register:', callback)
        self._callbacks.append(callback)
    def notify(self, *args, **kwargs):
        for callback in self._callbacks:
            callback(*args, **kwargs)
class EventHandler(object):
    def __init__(self, name):
        self.name = name
    def foo(self, *args, **kwargs):
        print('foo:', self …

class A(object):
    value = 5
    @classmethod
    def cls_fun(cls):
        print('A.cls_fun', cls, cls.value)
    def fun(self):
        print('A.fun', self, self.value)
        self.cls_fun()
class B(A):
    value = 10
class C(A):
    value = 15
    @classmethod
    def cls_fun(cls):
        print('B.cls_fun', cls, cls.value)
    def fun2(self):
        print …

class A(object):
    @staticmethod
    def static_fun():
        print('A.static_fun')

    def fun(self):
        print('A.fun', self)
        print('#', end='')
        self.static_fun()

class B(A):
    @staticmethod
    def static_fun():
        print('B.static_fun')

    def fun2(self):
        print('B.fun2', self)
        print('#', end='')
        self.static_fun()

a = A(); a.static_fun(); a.fun()
print('----')
b = B(); b …

class Field(object):
    def __get__(self, instance, owner):
        print('__get__', self, instance, self.name)
        return getattr(instance, self.name)
    def __set__(self, instance, value):
        print('__set__', self, instance, self.name, value)
        setattr(instance, self.name, value)

class Meta(type):
    def __new__(meta, name, bases, class_dict):
        print('__new__', name, bases, class_dict …

k = 3
x = [0] * k
y = [[0] * k] * k
z = [[0] * k for i in range(k)]

print(x, y, z)

x[0] = 1
x[1] = 2

y[0][0] = 1
y[0][1] = 2

z[0][0] = 1
z[0][1] = 2

print(x, y, z)

class A(object):
    def __init__(self):
        self.x = 5

    def __getattr__(self, name):
        print('    A.__getattr__', self, name)
        if name and name[0].isalpha():
            setattr(self, name, 10)
            return 10
        raise AttributeError('cannot get ' + name)

class B(A):
    def __getattribute__(self, name):
        print('    B.__getattribute__', self, name)
        if name == 'z …

class A(object):
    def __init__(self):
        self.x = 5
    def __getattr__(self, name):
        print('A.__getattr__(', self, ',', name, ')')
        setattr(self, name, 10)
        return 10
    def __setattr__(self, name, value):
        print('A.__setattr__(', self, ',', name, ',', value, ')')
        self.__dict__[name] = value

a = A()
print('P1:', a.x)
print('P2:', a.x)
a …

class Field(object):
    def __init__(self, name):
        self.name = '__' + name
    def __get__(self, instance, owner):
        print('__get__', self, instance, owner)
        return getattr(instance, self.name)
    def __set__(self, instance, value):
        print('__set__', self, instance, value)
        setattr(instance, self.name, value)

class Record(object):
    a = Field('a')
    b = Field('b …

a = 0
for x in range(3):
    a += 1

b = 0
for y in range(5):
    for z in range(8):
        b += 1

c = 0
for w in range(13):
    for w in range(23):
        c += 1

print(x, y, z, w)
print(a, b, c)

class Temperature(object):
    def __init__(self, celsius):
        self.celsius = celsius

    def get_fahrenheit(self):
        return self.celsius / 5 * 9 + 32

    def set_fahrenheit(self, fahrenheit):
        self.celsius = (fahrenheit - 32) / 9 * 5

    fahrenheit = property(get_fahrenheit, set_fahrenheit)

t = Temperature(30)
print(t.celsius, t.fahrenheit)
t.fahrenheit = 50
print(t.celsius, t.fahrenheit)

« Prev Page 2 / 4 Next »

Item 28: Bound Method

Item 27: classmethod

Item 26: staticmethod

Item 25: Metaclass

Item 24: List

Item 23: getattribute

Item 22: getattr and setattr

Item 21: Descriptors

Item 20: for Loop Variable

Item 19: Class Property

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