Python3.7 Kivy spinner瞬间崩溃

Question

和kivy一起尝试更多的东西，我在摆弄纺纱机。我一运行程序，就会显示以下错误：

   9: text: 'Music'
  10: values: root.musList
  11: on_value: lambda: showselection(self,self.text)

AttributeError:值

File "C:\Users\danburnier\AppData\Local\Continuum\anaconda3\lib\site-packages\kivy\lang\builder.py", line 725, in _apply_rule
raise AttributeError(key)

这是节目单

from kivy.uix.boxlayout import BoxLayout
from kivy.app import App
from kivy.lang import Builder
from os import listdir

Builder.load_string('''

<mycls>:
    BoxLayout:
        Spinner:
            size_hint: None, None
            size: 100, 44
            pos_hint: {'center': (.5, .5)}
            text: 'Music'
            values: root.musList
            on_value: lambda: showselection(self,self.text)
''')

class mycls(BoxLayout):

    musicList = []
    musDir = r'C:\Users\danburnier\Desktop\PythonPrograms'
    musList = listdir(musDir)

    def showselection(spinner,text):
        print(spinner,text)

class mineapp(App):
    def build(self):
        return mycls()

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

Answer 1

我认为这是文档中的一个错误。尝试替换：

        on_value: lambda: showselection(self,self.text)

与：

        on_text: root.showselection(self,self.text)