Python类方法重载

Question

我该怎么重载类的方法呢？我尝试过，但失败了：

class D(object):
    def create(self):
        foo = 100
        bar = 'squirrels'
        baz = 'I have %d insane %s in my head.' % (foo, bar)
        return baz     

class C(D):
    def create(self):
        super(C, self).create()
        baz = 'I have %s cute %s in my yard.' % (self.foo, self.bar)

C().create()

错误信息是：

AttributeError: 'C' object has no attribute 'foo'

Answer 1

在 D.create 这个函数里，你没有把变量放到 self 上，这就意味着变量 foo 只是这个函数内部的局部变量。

class D(object):
    def create(self):
        self.foo = 100
        self.bar = 'squirrels'
        self.baz = 'I have %d insane %s in my head.' % (self.foo, self.bar)
        return self.baz

Answer 2

你尝试把局部变量当作类的属性来使用。试着做以下的修改：

class D(object):
    def create(self):
        self.foo = 100
        self.bar = 'squirrels'
        baz = 'I have %d insane %s in my head.' % (self.foo, self.bar)
        return baz

class C(D):
    def create(self):
        super(C, self).create()
        print self.foo
        self.baz = 'I have %s cute %s in my yard.' % (self.foo, self.bar)

C().create()