Question

请查看以下代码段。你可以理解我想要做的事情。 PairTwo类的vlan_start必须从PortOne的值派生。我该怎么做？

>>> class G8032:
...     class PairOne:
...         vlan_start = 1101
...         vlan_count = 600
...     class PairTwo:
...         vlan_start = G8032.PairOne.vlan_start + G8032.PairOne.vlan_count
...         vlan_count = 400
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 5, in G8032
  File "<stdin>", line 6, in PairTwo
NameError: name 'G8032' is not defined
>>>

编辑：我在G8032中尝试了G8032.PairOne.vlan_***。它仍然无法运作。

Answer 1

不要嵌套这些课程。执行行vlan_start = G8032.PairOne.vlan_start + G8032.PairOne.vlan_count时，G8032类尚未完全定义。

如果您绝对需要支持您在评论中提到的语法（x = G8032.PairOne.vlan_start），那么可以（但可能不应）使用以下代码：

class PairOne:
    vlan_start = 1101
    vlan_count = 600


class PairTwo:
    vlan_start = PairOne.vlan_start + PairOne.vlan_count
    vlan_count = 40


class G8032:
    PairOne = PairOne
    PairTwo = PairTwo

print(G8032.PairOne.vlan_start)
print(G8032.PairTwo.vlan_start)
# 1101
# 1701

Answer 2

为什么不做这样的事情 -

class G8032:
    pass

class PairOne:
    vlan_start = 1101
    vlan_count = 600
class PairTwo:
    p = PairOne()
    vlan_start = p.vlan_start + p.vlan_count
    vlan_count = 400


if __name__ == "__main__":
    g = G8032()
    g.PairOne = PairOne()
    g.PairTwo = PairTwo()

您可能会发现此主题很有趣 - Nested classes' scope?

Answer 3

如果您需要上述语法，可以使用：

class G8032:
    PairOne = type('PairOne', (object,), dict({'vlan_start': 1101, 'vlan_count': 600}))
    PairTwo = type('PairTwo', (object,), dict({'vlan_start': PairOne.vlan_start + PairOne.vlan_count, 'vlan_count': 400 }))

print (G8032.PairOne.vlan_start)
>>> 1101

类中的嵌套类无法相互访问varibale

3 个答案: