传递给__init__()的参数不足

Question

下面的错误是什么？另外，有没有更好的方法来实现以下这些类？

     #!/usr/bin/python

     class Datacenters:
        def __init__(self,name,location,cpu,mem):
           self.name=name
           self.location=location
           self.cpu=cpu
           self.mem=mem

        def  getparam(self):
           return self.name,self.location ,self.cpu,self.mem

        def  getname(self):
           return self.name

     class WS(Datacenters):
        def __init__(self,name,location,cpu,mem,obj):
           #datacentername = Datacenters.__init__(self) #To which data center it is associated
           self.dcname =obj.name #To which data center it is associated

           Datacenters.__init__(obj,name,location,cpu,mem)

        def getparam(self,obj):
           self.name,self.location ,self.cpu,self.mem = obj.getparam()
           print self.dcname
           #return self.name,self.location ,self.cpu,self.mem,obj.name

        def  getwsname(self):
           return self.name

     class Pcs(WS):
        def __init__(self,name,location,cpu,mem,obj):
           self.wsname = obj.getwsname() #To which WS it is  associated
           WS.__init__(obj,name,location,cpu,mem)

        def  getparam(self,obj):
           print obj.getparam()
           print self.wsname


     a = Datacenters("dc1","Bl1",20,30)
     print a.getparam()
     b = WS("WS1","Bl1",21,31,a)
     print b.getparam(a)
     c = Pcs("PC1","Bl1",20,30,b)
     #print c.getparam(b)

输出：

   Press ENTER or type command to continue 
   ('dc1', 'Bl1', 20, 30)
   dc1
   None
   Traceback (most recent call last):
   File "class1.py", line 45, in <module>
   c = Pcs("PC1","Bl1",20,30,b)
   File "class1.py", line 34, in __init__
   WS.__init__(obj,name,location,cpu,mem)
   TypeError: __init__() takes exactly 6 arguments (5 given)

Answer 1

这个错误是因为你传了五个参数，但__init__需要六个。来数一数：

def __init__(self,name,location,cpu,mem,obj):

一共六个参数。你应该这样调用：

WS.__init__(obj,name,location,cpu,mem)

但是你只传了五个参数。第一个参数self缺失了。你应该问自己，为什么有时候不需要一直传六个参数。

这是因为当你在一个实例上调用方法时，self会自动传入。不过在这个情况下，你是直接在类上调用它，而不是在实例上调用。其实在这种情况下这样做没有必要，正确的写法是：

WS(obj,name,location,cpu,mem)

正如你上面提到的，确实可以在更上面的地方工作。