类型错误：缺少一个位置参数“self”康威生命游戏

Question

我一直在尝试写一个小程序，模拟康威的生命游戏。但是总是出现一个错误，提示 TypeError: step() missing 1 required positional argument: 'self'。我找了很多解决办法，但试了之后都没有用。

这是我的代码：

from tkinter import *
root = Tk()

class Cell (Button):
    Dead = 0
    Live = 1

    def __init__ (self,parent):
        Button.__init__(self,parent, relief = "raised" , width = 2 , borderwidth = 1 , command = self.onpress)
        self.displayState(Cell.Dead)

    def onpress (self):
        if self.state == Cell.Live:
            self.displayState(Cell.Dead)
        elif self.state == Cell.Dead:
            self.displayState(Cell.Live)

    def setNextState (self , Neighbours):
        if self.state == Cell.Live and (Neighbours < 2 or Neighbours > 3):
            self.nextState = Cell.Dead
        elif self.state == Cell.Dead and Neighbours == 3:
            self.nextState = Cell.Live
        elif self.state == Cell.Dead and Neighbours != 3:
            self.nextState = self.state

    def stepToNextState(self):
        self.displayState(self.nextState)

    def displayState (self , newstate):
        self.state = newstate
        if self.state == Cell.Live:
            self["bg"] = "black"
        if self.state == Cell.Dead:
            self["bg"] = "white"

class Grid:
    def __init__(self,parent,sizex,sizey):
        self.sizex = sizex
        self.sizey = sizey
        self.cells = []
        for a in range (0,self.sizex):
            rowcells = []
            for b in range (0, self.sizey):
                c = Cell(parent)
                c.grid(row=b , column=a)
                rowcells.append(c)
            self.cells.append(rowcells)

    def step (self):
        cells = self.cells
        for x in range (0,self.sizex):
            if x==0: x_down = self.sizex-1
            else: x_down = x-1
            if x==self.sizex-1: x_up = 0
            else: x_up = x+1
            for y in range(0,self.sizey):
                if y==0: y_down = self.sizey-1
                else: Y_down = y-1
                if y==self.sizey-1: y_up = 0
                else: y_up = y+1
                sum = cells[x_down][y].state + cells[x_up][y].state + cells[x][y_down].state + cells[x][y_up].state + cells[x_down][y_down].state +cells[x_up][y_up].state + cells[x_down][y_up].state + cells[x_up][y_down].state
            cells[x][y].setNextState(sum)
            for row in cells:
                for cell in row:
                    cell.stepToNextState()

    def clear(self):
        for row in self.cells:
            for cell in row:
                 cell.displayState(Cell.Dead)

def GridStep():
    Grid.step()

def GridClear():
    Grid.step()

if __name__ == "__main__":
    frame = Frame(root)
    frame.pack()
    grid = Grid(frame,25,25)
    bottomFrame = Frame(root)
    bottomFrame.pack (side = BOTTOM)
    buttonStep = Button(bottomFrame , text="Step" , command=GridStep)
    buttonStep.pack(side = LEFT)
    buttonClear = Button(bottomFrame, text = "Clear", command=GridClear)
    buttonClear.pack(side=LEFT , after=buttonStep)
    root.mainloop()

Answer 1

你有两个函数，它们直接在类上调用了未绑定的方法：

def GridStep():
    Grid.step()

def GridClear():
    Grid.step()

Grid 是类本身，而不是类的一个实例。调用 Grid.step() 时不会提供 self 参数，因为没有实例可以把 self 绑定到上面。你需要在这里提供一个 Grid 的实例，然后在那个实例上调用方法。

所以，不要在你的按钮上使用 GridStep 和 GridClear，你需要从你创建的 grid 对象中传递方法：

grid = Grid(frame,25,25)
bottomFrame = Frame(root)
bottomFrame.pack (side = BOTTOM)
buttonStep = Button(bottomFrame , text="Step" , command=grid.step)
buttonStep.pack(side = LEFT)
buttonClear = Button(bottomFrame, text = "Clear", command=grid.clear)
buttonClear.pack(side=LEFT , after=buttonStep)

注意，我是把绑定的方法传给 command，但它们还没有被调用。

这样的话，你可以完全去掉 GridStep 和 GridClear 这两个函数。