python class init 用法

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

    def method_a(self, foo):
        print self.x + ' ' + foo
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class Point:
    def __init__(self, x, y):
        self._x = x
        self._y = y

x = Point(1,2)
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class MyClass(object):
    i = 123
    def __init__(self):
        self.i = 345
     
a = MyClass()
print(a.i)
print(MyClass.i)

#out
345
123
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参考
https://stackoverflow.com/questions/625083/what-do-init-and-self-do-in-python