Das deutsche Python-Forum

Code: Alles auswählen

def foo(x, y, z, register_undo):

    # irgendwas mit x, y, z machen
    
    @register_undo
    def undo_foo():
        # irgendwas mit x, y, z wieder rückgängig machen


def main():
    undo_stack = []
    ...
    foo(a, b, c, undo_stack.append)
    ...
    undo_stack.pop()()


if __name__ == "__main__":
    main()

Code: Alles auswählen

def foo(x, y, z, register_undo):

    x +=5
    
    @register_undo
    def undo_foo():
        x -=5


def main():
    a, b, c = 1, 2, 3

    undo_stack = []
    
    foo(a, b, c, undo_stack.append)
    
    undo_stack.pop()()


if __name__ == "__main__":
    main()

Code: Alles auswählen

UnboundLocalError: cannot access local variable 'x' where it is not associated with a value

Code: Alles auswählen

# modul xyz

x = 1

def bar():
    x = 2
    print(x)

bar()

print(x)

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2
1

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class Baz:
    def __init__(self):
        self.x = 123
        self._undo_list = []
    def undo(self):
        if self._undo_list:
            self._undo_list.pop()
    def foo(self):
        self.x += 5
        @self._undo_list.append
        def undo_foo():
            self.x -= 5
            
b = Baz()
print(b.x)  # -> 123
b.foo()
print(b.x)  # -> 128
b.undo()
print(b.x)  # -> 123

Code: Alles auswählen

    @register_undo
    def undo_foo():
        print(x)