I want to pass in 2 things for a function but one is in another function and the function which I need the return is called in a lambda. What do I do?

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英文:

I want to pass in 2 things for a function but one is in another function and the function which I need the return is called in a lambda. What do I do?

问题

以下是翻译好的部分:

我需要为一个函数传递2个额外参数,但是参数 b - 只能是 b1、b2 或 b3 - 位于一个函数后面,但它在一个 lambda 内部调用,所以当我尝试创建一个新变量 - pb1 - 时,它不起作用。

我期望它能够正常工作,并且被按下的按钮 - pb1 - 被传递到 checkwin,然后传递到 checkwinpos,但它没有工作。错误消息如下:

b1 = Button(root, text="Rock", height=3, width=6, bg="SystemButtonFace", command=lambda: [pb1 = b1_click(b1)])
                                                                                                  ^^^^^^^^^^^^^^^^^^
SyntaxError: 无效的语法也许你想要使用 '=='':=' 而不是 '='
英文:

I need to pass in 2 more parameters for a function but b - which can only be b1, b2 or b3 - is behind a function but it is called inside of a lambda so when I try and make a new variable - pb1 - it doesn't work.

def b1_click(b):
  global p1
  p1 = p1.join(b["text"])
  b4.config(state=ACTIVE)
  b5.config(state=ACTIVE)
  b6.config(state=ACTIVE)
  b1.config(state=DISABLED)
  b2.config(state=DISABLED)
  b3.config(state=DISABLED)
  return b


def b2_click(b):
  global p2
  p2 = p2.join(b["text"])
  b4.config(state=DISABLED)
  b5.config(state=DISABLED)
  b6.config(state=DISABLED)

def checkwin(b, bb):
  possibilities = [{"Rock", "Scissors"}, {"Scissors", "Paper"}, {"Paper", "Rock"}]
  
  for possibility in possibilities:
    checkwinpos(*possibility, b, bb)

def checkwinpos(win, lose, b, bb):
  if b["text"] == win and bb["text"] == lose:
    b.config(bg="Green")
    bb.config(bg="Red")
  elif bb["text"] == win and b["text"] == lose:
    bb.config(bg="Green")
    b.config("Red")
  else:
    messagebox.showinfo("Jensen The Great's Rock Paper Scissors", "You both picked the same thing")
  

root = Tk()
root.title("Jensen The Great's Rock Paper Scissors")
root.geometry("1200x710")

b1 = Button(root, text = "Rock", height = 3, width = 6, bg="SystemButtonFace", command=lambda: [pb1 = b1_click(b1)])
b2 = Button(root, text = "Paper", height = 3, width = 6, bg="SystemButtonFace", command=lambda: [pb1 = b1_click(b2)])
b3 = Button(root, text = "Scissors", height = 3, width = 6, bg="SystemButtonFace", command=lambda: [pb1 = b1_click(b3)])

b4 = Button(root, text = "Rock", height = 3, width = 6, bg="SystemButtonFace", command=lambda: [b2_click(b4), checkwin(pb1, b4)])
b5 = Button(root, text = "Paper", height = 3, width = 6, bg="SystemButtonFace", command=lambda: [b2_click(b5), checkwin(pb1, b5)])
b6 = Button(root, text = "Scissors", height = 3, width = 6, bg="SystemButtonFace", command=lambda: [b2_click(b6), checkwin(pb1, b6)])

b4.config(state=DISABLED)
b5.config(state=DISABLED)
b6.config(state=DISABLED)

I was expecting it to work and the button which was pressed - pb1 - to be passed into checkwin and then passed into checkwinpos but it didn't work. The error message is here:

    b1 = Button(root, text = "Rock", height = 3, width = 6, bg="SystemButtonFace", command=lambda: [pb1 = b1_click(b1)])
                                                                                                    ^^^^^^^^^^^^^^^^^^
SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?

答案1

得分: 1

是的,错误消息是正确的。等号 ' = ' 是一个赋值运算符,不能在 lambda 函数内使用,因为它不是一个有效的表达式。

要修复这个错误,你可以在 lambda 函数内用等于运算符 ' == ' 替换等号 ' = '。下面是修正后的代码:

b1 = Button(root, text="Rock", height=3, width=6, bg="SystemButtonFace", command=lambda: [b1_click(b1)])

或者,你可以在 lambda 函数内使用獭运算符 ':=' 代替等号 ' = ',就像这样:

b1 = Button(root, text="Rock", height=3, width=6, bg="SystemButtonFace", command=lambda: [pb1 := b1_click(b1)])

不过,请注意,獭运算符只在 Python 3.8 或更高版本中可用。

英文:

Yes, the error message is correct. The equal sign '=' is an assignment operator and cannot be used within a lambda function, as it is not a valid expression.

To fix the error, you can replace the equal sign '=' with the equal-to operator '==' within the lambda function. Here's the corrected code:
‍‍‍‍‍

b1 = Button(root, text="Rock", height=3, width=6, bg="SystemButtonFace", command=lambda: [b1_click(b1)])

Alternatively, you could use the walrus operator ':=' instead of the equal sign '=' within the lambda function, like this:

b1 = Button(root, text="Rock", height=3, width=6, bg="SystemButtonFace", command=lambda: [pb1 := b1_click(b1)])

However, note that the walrus operator is only available in Python 3.8 or higher.

huangapple
  • 本文由 发表于 2023年4月10日 21:09:59
  • 转载请务必保留本文链接:https://go.coder-hub.com/75977429.html
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