绑定多个语句以在 kivy 中尝试表达式

Question

我想对 kv 文件中的 kivy 按钮执行与以下代码相同的操作

try:
  print"first action"
  print"second action"
except:
  print"there was an error"

这是我想要在其中执行该按钮的 kv 文件和按钮我收到错误消息：

on_release: 
  try: \
    print("first action")
    #first action is working but second is not working
    print('second action'):

  except:\
    print("it is not working")

它给我这样的错误：

[INFO   ] [Logger      ] Record log in /root/.kivy/logs/kivy_15-06-28_29.txt
[INFO   ] [Kivy        ] v1.9.0
[INFO   ] [Python      ] v2.7.3 (default, Jan  2 2013, 16:53:07) 
[GCC 4.7.2]
[INFO   ] [Factory     ] 173 symbols loaded
[INFO   ] [Image       ] Providers: img_tex, img_dds, img_gif, img_pygame, img_pil (img_ffpyplayer ignored)
[INFO   ] [Window      ] Provider: pygame(['window_egl_rpi'] ignored)
[WARNING] [WinPygame   ] Video: failed (multisamples=2)
[WARNING] [WinPygame   ] trying without antialiasing
[INFO   ] [GL          ] OpenGL version <2.1 Mesa 8.0.5>
[INFO   ] [GL          ] OpenGL vendor <VMware, Inc.>
[INFO   ] [GL          ] OpenGL renderer <Gallium 0.4 on SVGA3D; build: RELEASE;  >
[INFO   ] [GL          ] OpenGL parsed version: 2, 1
[INFO   ] [GL          ] Shading version <1.20>
[INFO   ] [GL          ] Texture max size <8192>
[INFO   ] [GL          ] Texture max units <16>
[INFO   ] [Window      ] virtual keyboard not allowed, single mode, not docked
[INFO   ] [Text        ] Provider: pygame
 Traceback (most recent call last):
   File "main.py", line 128, in <module>
     ExampleApp().run()
   File "/usr/local/lib/python2.7/dist-packages/kivy/app.py", line 797, in run
     self.load_kv(filename=self.kv_file)
   File "/usr/local/lib/python2.7/dist-packages/kivy/app.py", line 594, in load_kv
     root = Builder.load_file(rfilename)
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1749, in load_file
     return self.load_string(data, **kwargs)
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1796, in load_string
     parser = Parser(content=string, filename=fn)
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1185, in __init__
     self.parse(content)
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1291, in parse
     rule.precompile()
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1053, in precompile
     x.precompile()
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1053, in precompile
     x.precompile()
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1053, in precompile
     x.precompile()
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1053, in precompile
     x.precompile()
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1053, in precompile
     x.precompile()
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1053, in precompile
     x.precompile()
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1051, in precompile
     x.precompile()
   File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 976, in precompile
     self.co_value = compile(value, self.ctx.filename or '<string>', mode)
   File "./example.kv", line 180
     print("second action")
         ^
 SyntaxError: invalid syntax

那么有什么解决办法吗？在 try 语句后做多个事情？

Answer 1

我认为 kv lang 不支持异常。将您的代码移至 Python class:

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.lang import Builder

Builder.load_string("""
<Test>:
    Button:
        text: "..."
        on_press: root.react()
""")

class Test(FloatLayout):
    def react(self):
        try:
            print("first action")
            print("second action")
        except:
            print("there was an error")

class TabbedPanelApp(App):
    def build(self):
        return Test()

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

简单地打印几次很容易：

Builder.load_string("""
<Test>:
    Button:
        text: "..."
        on_press:
            print("first action")
            print("second action")            
""")

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