Python KV文件如何从另一个类调用函数

问题描述

如何从kv文件中的Account类调用方法?

How can I call a method from class Account in my kv file?

py文件:

import kivy
kivy.require("1.10.1")
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.widget import Widget
class Account():
def __init__(self,name, balance):
    self.name = name
    self.__balance__ = balance
def getBalance(self):
    return (self.__balance__)
def setBalance(self, zmena):
    self.__balance__ = self.__balance__+zmena
acc = Account("Account1", "1000")
class myWidget(Widget):
Builder.load_file("MP.kv")
class MainApp(App):
def build(self):
    return myWidget()
if __name__ == "__main__":
MainApp().run()

kv文件:

#:kivy 1.10.1

<Button>
background_color: 0.1, 0.1, 0.9, 0.9
font_size: 22
<Label>
background_color: 0.1, 0.1, 0.9, 0.9
font_size: 22

<myWidget>:
Label:
    id: lb
    text: "Account"
    pos: root.width /2-self.width/2, root.top/2+200
Label:
    id: lb1
    text: "Account name"
    pos: root.width /2-self.width/2, root.top/2+150
Label:
    id: lb2
    text: "balance"   '''here i want call methot getBalance, but how?
    pos: root.width /2-self.width/2, root.top/2+100
Label:
    id: lb3
    text: "Add/sub money"
    pos: root.width /2-self.width/2, root.top/2+50
TextInput:
    id: tp
    text: "money"
    pos: root.width /2-self.width/2, root.top/2-50
    size_hint: .5, .25
Button:
    id: btn1
    text: "Confirm"
    size_hint: .5, .25
    pos: root.width /2-self.width/2, root.top/2-150

推荐答案

问题#2

解决方案2

使用Kivy属性，例如StringProperty，因为它们会产生事件，这样，当对象的属性发生更改时，所有引用该属性的属性都会自动更新.

Solution #2

Use Kivy Properties e.g. StringProperty, because they produce events such that when an attribute of your object changes, all properties that reference that attribute are automatically updated.

import kivy

kivy.require("1.10.1")
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.widget import Widget
from kivy.properties import ObjectProperty, StringProperty


class Account():
    def __init__(self, name, balance):
        self.name = name
        self.__balance__ = balance

    def getBalance(self):
        return (self.__balance__)

    def setBalance(self, zmena):
        self.__balance__ = self.__balance__ + zmena


class myWidget(Widget):
    acc = ObjectProperty(None)
    balance = StringProperty('')

    def __init__(self, **kwargs):
        super(myWidget, self).__init__(**kwargs)
        self.acc = Account("Account1", 1008)
        self.update_balance()

    def update_balance(self):
        self.balance = str(self.acc.getBalance())


Builder.load_file("MP.kv")


class MainApp(App):
    def build(self):
        return myWidget()


if __name__ == "__main__":
    MainApp().run()

MP.kv

#:kivy 1.10.1

<Button>:
    background_color: 0.1, 0.1, 0.9, 0.9
    font_size: 22

<Label>:
    background_color: 0.1, 0.1, 0.9, 0.9
    font_size: 22

<myWidget>:
    Label:
        id: lb
        text: "Account"
        pos: root.width /2-self.width/2, root.top/2+200
    Label:
        id: lb1
        text: "Account name"
        pos: root.width /2-self.width/2, root.top/2+150
    Label:
        id: lb2
        text: root.balance
        pos: root.width /2-self.width/2, root.top/2+100
    Label:
        id: lb3
        text: "Add/sub money"
        pos: root.width /2-self.width/2, root.top/2+50
    TextInput:
        id: tp
        hint_text: "money"
        pos: root.width /2-self.width/2, root.top/2-50
        size_hint: .5, .25
    Button:
        id: btn1
        text: "Confirm"
        size_hint: .5, .25
        pos: root.width /2-self.width/2, root.top/2-150
        on_release:
            root.acc.setBalance(int(tp.text))
            root.update_balance()

输出#2

1. 为Kivy ObjectProperty添加导入语句，例如from kivy.properties import ObjectProperty
2. 声明Kivy ObjectProperty，例如acc = ObjectProperty(None)
3. myWidget()的实现构造函数方法

1. Add import statement for Kivy ObjectProperty e.g. from kivy.properties import ObjectProperty
2. Declare a Kivy ObjectProperty, e.g. acc = ObjectProperty(None)
3. Implement constructor method for myWidget()

kv文件

应用启动时，acc为无".因此，我们需要检查无"以避免错误.

kv file

When the app start, acc is None. Therefore, we need to check for None to avoid error.

text: '' if root.acc is None else root.acc.getBalance()

示例

main.py

import kivy

kivy.require("1.10.1")
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.widget import Widget
from kivy.properties import ObjectProperty


class Account():
    def __init__(self, name, balance):
        self.name = name
        self.__balance__ = balance

    def getBalance(self):
        return (self.__balance__)

    def setBalance(self, zmena):
        self.__balance__ = self.__balance__ + zmena


class myWidget(Widget):
    acc = ObjectProperty(None)

    def __init__(self, **kwargs):
        super(myWidget, self).__init__(**kwargs)
        self.acc = Account("Account1", "1000")


Builder.load_file("MP.kv")


class MainApp(App):
    def build(self):
        return myWidget()


if __name__ == "__main__":
    MainApp().run()

MP.kv

#:kivy 1.10.1

<Button>:
    background_color: 0.1, 0.1, 0.9, 0.9
    font_size: 22

<Label>:
    background_color: 0.1, 0.1, 0.9, 0.9
    font_size: 22

<myWidget>:
    Label:
        id: lb
        text: "Account"
        pos: root.width /2-self.width/2, root.top/2+200
    Label:
        id: lb1
        text: "Account name"
        pos: root.width /2-self.width/2, root.top/2+150
    Label:
        id: lb2
        text: '' if root.acc is None else root.acc.getBalance()
        pos: root.width /2-self.width/2, root.top/2+100
    Label:
        id: lb3
        text: "Add/sub money"
        pos: root.width /2-self.width/2, root.top/2+50
    TextInput:
        id: tp
        text: "money"
        pos: root.width /2-self.width/2, root.top/2-50
        size_hint: .5, .25
    Button:
        id: btn1
        text: "Confirm"
        size_hint: .5, .25
        pos: root.width /2-self.width/2, root.top/2-150

输出

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