Question

我可以强制父类调用派生类的函数版本吗？

class Base(object):
    attr1 = ''
    attr2 = ''

    def virtual(self):
        pass               # doesn't do anything in the parent class

    def func(self):
        print "%s, %s" % (self.attr1, self.attr2)
        self.virtual()

和一个派生自它的类

class Derived(Base):
    attr1 = 'I am in class Derived'
    attr2 = 'blah blah'

    def virtual(self):
        # do stuff...
        # do stuff...

清除模糊：

d = Derived()
d.func()         # calls self.virtual() which is Base::virtual(), 
                 #  and I need it to be Derived::virtual()

Answer 1

如果您实例化Derived（说d = Derived()），则.virtual 调用的d.func() Derived.virtual。如果没有涉及Derived的实例，则self没有合适的Derived.virtual，因此当然无法调用它。

Answer 2

这并非不可能 - 实际上有一种解决方法，你不必传递函数或类似的东西。我自己正在开展一个项目，这个问题出现了。这是解决方案：


class Base(): # no need to explicitly derive object for it to work
    attr1 = 'I am in class Base'
    attr2 = 'halb halb'

    def virtual(self):
        print "Base's Method"

    def func(self):
        print "%s, %s" % (self.attr1, self.attr2)
        self.virtual()

class Derived(Base):
    attr1 = 'I am in class Derived'
    attr2 = 'blah blah'

    def __init__(self):
  # only way I've found so far is to edit the dict like this
        Base.__dict__['_Base_virtual'] = self.virtual

    def virtual(self):
        print "Derived's Method"

if __name__ == '__main__':
    d = Derived()
    d.func()

Answer 3

好的，我刚刚传递了虚拟（）的实例，我需要func（）

class Base(object):
    attr1 = ''
    attr2 = ''

    def __init__(self):
        pass

    def virtual(self):
        pass

    def func(self, cb):
         print "%s, %s" % (self.attr1, self.attr2)
         cb()

class Derived(Base):
    attr1 = 'I am in class Derived'
    attr2 = 'blah blah'

    def virtual(self):
        # do stuff...
        # do stuff...


d = Derived()
d.func(d.virtual)

Python在父类中使用派生类的方法？

3 个答案: