在 Python 中显示属性沮丧

Question

我一直在观看 Kivy 和 Python 关于创建计算器的教程，但我看到了这个属性：显示小部件 ID 的值。使用此值，它可以访问小部件的其他属性。这是代码（.kv 文件）：

<CalcGridLayout>:
    id: calculator
    display: entry #this is the display property
    rows: 5
    padding: 10
    spacing: 10

    BoxLayout:
        TextInput:
            id: entry #with the value of this
            font_size: 32
            multiline: False

    BoxLayout:
        spacing: 10
        Button:
            text: "7"
            on_press: entry.text += self.text
        Button:
            text: "8"
            on_press: entry.text += self.text
        Button:
            text: "9"
            on_press: entry.text += self.text
        Button:
            text: "+"
            on_press: entry.text += self.text

    BoxLayout:
        spacing: 10
        Button:
            text: "4"
            on_press: entry.text += self.text
        Button:
            text: "5"
            on_press: entry.text += self.text
        Button:
            text: "6"
            on_press: entry.text += self.text
        Button:
            text: "-"
            on_press: entry.text += self.text

    BoxLayout:
        spacing: 10
        Button:
            text: "1"
            on_press: entry.text += self.text
        Button:
            text: "2"
            on_press: entry.text += self.text
        Button:
            text: "3"
            on_press: entry.text += self.text
        Button:
            text: "*"
            on_press: entry.text += self.text

    BoxLayout:
        spacing: 10
        Button:
            text: "AC"
            on_press: entry.text = ""
        Button:
            text: "0"
            on_press: entry.text += self.text
        Button:
            text: "="
            on_press: calculator.calculate(entry.text)
        Button:
            text: "/"
            on_press: entry.text += self.text

那是什么variable/property？它有什么用？

Answer 1

参考你的kv文件：

calc.kv

display: entry

main.py

display = ObjectProperty(None)

display - 是您的变量，它被声明为 Kivy ObjectProperty。它用于引用在 kv 文件中实例化的 TextInput 子控件。在声明一个 ObjectProperty 之后，您将它连接到在 kv 文件中创建的子部件，例如display: entry。完成后，您可以轻松地在 calculate 方法中引用 TextInput 属性。

示例

main.py

from kivy.app import App
from kivy.uix.gridlayout import GridLayout
from kivy.properties import ObjectProperty


class CalcGridLayout(GridLayout):
    display = ObjectProperty(None)

    def calculate(self, dt):
        print(self.display.text)


class CalcApp(App):

    def build(self):
        return CalcGridLayout()


if __name__ == '__main__':
    CalcApp().run()

calc.kv

#:kivy 1.10.0

<CalcGridLayout>:
    id: calculator
    display: entry #this is the display property
    rows: 5
    padding: 10
    spacing: 10

    BoxLayout:
        TextInput:
            id: entry #with the value of this
            font_size: 32
            multiline: False

    BoxLayout:
        spacing: 10
        Button:
            text: "7"
            on_press: entry.text += self.text
        Button:
            text: "8"
            on_press: entry.text += self.text
        Button:
            text: "9"
            on_press: entry.text += self.text
        Button:
            text: "+"
            on_press: entry.text += self.text

    BoxLayout:
        spacing: 10
        Button:
            text: "4"
            on_press: entry.text += self.text
        Button:
            text: "5"
            on_press: entry.text += self.text
        Button:
            text: "6"
            on_press: entry.text += self.text
        Button:
            text: "-"
            on_press: entry.text += self.text

    BoxLayout:
        spacing: 10
        Button:
            text: "1"
            on_press: entry.text += self.text
        Button:
            text: "2"
            on_press: entry.text += self.text
        Button:
            text: "3"
            on_press: entry.text += self.text
        Button:
            text: "*"
            on_press: entry.text += self.text

    BoxLayout:
        spacing: 10
        Button:
            text: "AC"
            on_press: entry.text = ""
        Button:
            text: "0"
            on_press: entry.text += self.text
        Button:
            text: "="
            on_press: calculator.calculate(entry.text)
        Button:
            text: "/"
            on_press: entry.text += self.text

在 Python 中显示属性沮丧

Display property in Python Kivy

python

android

python-3.x

kivy

kivy-language

calc.kv

main.py

示例

main.py

calc.kv

在 Python 中显示 属性 沮丧

Display property in Python Kivy

python

android

python-3.x

kivy

kivy-language

calc.kv

main.py

示例

main.py

calc.kv

在 Python 中显示属性沮丧