如何使用子类的默认值调用父类的init? [英] How to call parent class init with default values from child class?
问题描述
我正在尝试为子类提供默认变量,并在文件变胖时停止重复代码:
I am trying to give my subclasses default variables and stop duplicating code as the file is getting fat:
class Base(object):
def __init__(self, username=None, password=None, start_url=None):
self.username = username
self.password = password
self.start_url = start_url
class Subclass(Base):
def __init__(self, username="hoss_it87", password="whatsgoodSO", start_url="www.boss-sauce.com"):
super(Subclass, self).__init__()
Base
当然可以,但是我希望Subclass
以相同的方式初始化,只是用真实的字符串覆盖None
(当然,所有登录样式都是相似的).
Base
works of course, but I want Subclass
to init the same way, just overriding the None
with real strings (all login styles are similar of course).
In [12]: x = Base('myuser', 'mypassword', 'www.google.com')
In [13]: x.username
Out[13]: 'myuser'
In [14]: x.start_url
Out[14]: 'www.google.com'
In [15]: y = Subclass()
In [16]: y.username
In [17]: y.start_url
In [18]: y.password
In [19]:
为什么对于Subclass
属性我什么也没得到,怎么解决?谢谢
Why do I get nothing for Subclass
attributes, and how can I fix it? Thank you
请注意,删除基类默认设置会导致其他问题
Please note removing base class defaults causes other issues
class Base(object):
def __init__(self, username, password, start_url):
self.username = username
self.password = password
self.start_url = start_url
class Subclass(Base):
def __init__(self, username="honeybooboosbiggestfan", password="toomuchburkerking", start_url="www.imjokingiprefericeroadtruckers.com"):
super(Subclass, self).__init__()
In [24]: y = Subclass()
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-24-55b9b4fdf93b> in <module>()
----> 1 y = Subclass()
<ipython-input-23-a9dc62450db7> in __init__(self, username, password, start_url)
9
10 def __init__(self, username="honeybooboosbiggestfan", password="toomuchburkerking", start_url="www.imjokingiprefericeroadtruckers.com"):
---> 11 super(Subclass, self).__init__()
TypeError: __init__() takes exactly 4 arguments (1 given)
In [25]:
已解决:
class Base(object):
def __init__(self, username, password, start_url):
self.username = username
self.password = password
self.start_url = start_url
class Subclass(Base):
def __init__(self, username="honeybooboosbiggestfan", password="toomuchburkerking", start_url="www.imjokingiprefericeroadtruckers.com"):
super(Subclass, self).__init__(username=username, password=password, start_url=start_url)
## -- End pasted text --
In [26]: y = Subclass()
In [27]: y.username
Out[27]: 'honeybooboosbiggestfan'
In [28]:
推荐答案
您必须将参数从SubClass
init传递给Base
的init块:
You have to pass the arguments from the SubClass
init to the init block of Base
:
class Subclass(Base):
def __init__(self, username="hoss_it87", password="whatsgoodSO", start_url="www.boss-sauce.com"):
super(Subclass, self).__init__(username=username, password=password, start_url=start_url)
在您的代码中,调用Base
的init时不带参数,因此采用其默认参数,它们都是None
.
In your code, the Base
init is called without arguments and thus takes its default arguments, which are all None
.
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