Question

因此，我尝试使用kivy框架编写简单的代码，我的代码通过字典查找某个值，该值在以后的阶段告诉我的代码哪些字典值需要作为下拉菜单输出，哪些输出dict值仅需要作为常规标签和文本输入输出。现在的问题出在我正在浏览的字典中描述了多个需要下拉的值。我希望下拉菜单的工作方式是，在下拉菜单中选择一个值来触发下拉菜单时，必须将文本更改为单击的按钮的文本。这是代码，我决定编写一个更简单的版本以供阅读。我想在代码下键入此代码，但我真的很想在堆栈Over Flow上写问题。您要查看的代码将创建两个按钮（触发下拉菜单），一个名为组0，另一个名为组1，但是当我单击组0下的一个下拉按钮时，组1的文本属性会更改，但是我实际上想更改组0按钮的text属性。当我解释时，我的代表没有任何意义，因此请告诉我是否需要澄清，我们将不胜感激。

from kivy.app import App

from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout

test_floatie = FloatLayout()
# We wanna create 2 button that trigger a drop down
i = 0

# The loop that creates the two buttons
while i < 2:

# Create a drop down
    dropdown = DropDown()
    for index in range(10):

        # Creating our button
        btn = Button(text="Button"+str(index), size_hint_y=None, height=44)

        # Sending button info to dropdown select function
        btn.bind(on_release=lambda btn: dropdown.select(btn.text))

        # Closing drop down after selection
        btn.bind(on_release=dropdown.dismiss)

        # Adding buttons to the drop down
        dropdown.add_widget(btn)

    # Simple if statement for positioning
    if i == 0:
        position = "left"
    else:
        position = "right"

    # The button that triggers the drop down
    dropButton = Button(text="Group"+str(i), size_hint=(0.4, 0.3), pos_hint={"top":1, position:1})
    print(dropButton)

    # Binding the button to a function that triggers the drop down 
    dropButton.bind(on_release=dropdown.open)

    # Using the drop down select function to change the text of the button that triggers the drop down
    dropdown.bind(on_select=lambda instance, x: setattr(dropButton, "text", x))

    test_floatie.add_widget(dropButton)

    i = i +1

# Running la app
class MainApp(App):
    def build(self):
        return test_floatie

MainApp().run()

Answer 1

稍微简化了代码：

from functools import partial

test_floatie = FloatLayout()
# We wanna create 2 button that trigger a drop down


def select(drop_button, text, btn):
    drop_button.text = text


# The loop that creates the two buttons
for position in ["left", "right"]:
    # The button that triggers the drop down
    dropButton = Button(text="Group " + position, size_hint=(0.4, 0.3),
                        pos_hint={"top": 1, position: 1})

    # Create a drop down
    dropdown = DropDown()
    for index in range(10):
        # Creating our button
        btn = Button(text=position + str(index), size_hint_y=None, height=44)

        # Sending button info to dropdown select function
        # btn.bind(on_release=lambda btn: setattr(dropButton, "text", btn.text))
        # btn.bind(on_release=lambda btn: select(dropButton, btn.text, btn))
        btn.bind(on_release=partial(select, dropButton, btn.text))

        # Closing drop down after selection
        btn.bind(on_release=dropdown.dismiss)

        # Adding buttons to the drop down
        dropdown.add_widget(btn)

    # Binding the button to a function that triggers the drop down
    dropButton.bind(on_release=dropdown.open)

    test_floatie.add_widget(dropButton)


# Running la app
class MainApp(App):
    def build(self):
        return test_floatie


MainApp().run()

请注意使用partial而不是已注释掉的lambda。
看来他们是同谋，但事实并非如此。（请参阅here）

如果要在循环中创建回调，并使用循环变量作为回调的参数，则应使用partial。 lambda在运行时评估变量，而partial在创建partial函数时评估。

多个猕猴桃下拉

1 个答案: