Python无法在类中分配值

问题描述：

我无法在类中传递/分配值。这是我的班级定义，基本上我想根据时间（一天中的时间）更改颜色。Python无法在类中分配值

class Meter(tk.Canvas): 

    def __init__(self,master,*args,**kwargs): 
     super(Meter,self).__init__(master,*args,**kwargs) 

     self.tod=tod 
     self.layoutparams(tod) 
     self.graphics() 
     self.createhand() 
     self.setrange() 


    def layoutparams(self,tod): 
     # set parameters that control the layout 
     height = int(self['height']) 
     width = int(self['width']) 


     # find a square that fits in the window 
     if(height*2 > width): 
      side = width 
     else: 
      side = height*2 

     # set axis for hand 
     self.centrex = side/2 
     self.centrey = side/2 

     # standard with of lines 
     self.linewidth = 2 

     # outer radius for dial 
     self.radius = int(0.40*float(side)) 

     # set width of bezel 
     self.bezel = self.radius/15 
     self.bezelcolour1 = 'green' 
here is where i change the colour 
     if (tod=='day'): 
      self.bezelcolour2 = 'black' 
     else: 
      self.bezelcolour2 = 'white' 
     self.bezelcolour3 = 'red' 

     # set lengths of ticks and hand 
     self.majortick = self.radius/8 
     self.minortick = self.majortick/2

这里是我该怎么办实例

w=Meter(self,height = 400,width = 400) 
    w.tod='day'

我收到此错误

line 27, in __init__ 
    self.tod=tod 
NameError: name 'tod' is not defined

有什么不对？

答

问题正是错误告诉你的。您将tod的值指定为self.tod，但您没有名为tod的变量。

答

你必须写：

w=Meter(self,height = 400,width = 400, tod='day')

，这将是更好的写：

if (self.tod=='day'):

你或许应该还添加了一个功能changeTod。

Python无法在类中分配值

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