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Flexx for Python: how to get PyComponent instance outside of the app context (watchdog EventHandler)



2019 Community Moderator ElectionHow do I copy a file in Python?How can I safely create a nested directory in Python?How to get the current time in PythonHow can I make a time delay in Python?Getting the class name of an instance?Getting the last element of a list in PythonHow to get the number of elements in a list in Python?How to concatenate two lists in Python?How to use threading in Python?How to lowercase a string in Python?










0















I'm currently diving into Flexx for making a UI to my Python program. I'm starting to get the hang of it but I'm running into a problem.



I need to be able to call a PyComponent's method from outside the scope of the App. I understand that app.cls gives the class that was used to instanciate the App, but it's not the actual instance, so I can't do something like app.cls.my_method(...).



Is there a way to get the instance of the component inside the app wrapper, only knowing the App instance?



Thanks!



EDIT: After looking at the source, I found the mostly undocumented AppManager and Session definitions and could get a reference to the component's instance with:



from flexx.app import manager
app_instance = manager.get_connections('MyAppName')[0].app


But if I call one of its methods from a watchdog.events.FileSystemEventHandler instantiated by the watchdog library, I get the following traceback:



 File "myfile.py", line 37, in on_created
manager.get_connections('MyAppName')[0].app.update_verbose(False)
File "libsite-packagesflexxevent_action.py", line 150, in __call__
if loop.can_mutate(ob):
File "libsite-packagesflexxevent_loop.py", line 85, in can_mutate
active = self.get_active_component()
File "libsite-packagesflexxevent_loop.py", line 103, in get_active_component
if len(self._local._active_components) > 0:
AttributeError: '_thread._local' object has no attribute '_active_components'


Note that update_verbose is a Flexx action that mutates a property. I suspect an issue where the watchdog handler is running on a different thread but I can't see what to change...










share|improve this question




























    0















    I'm currently diving into Flexx for making a UI to my Python program. I'm starting to get the hang of it but I'm running into a problem.



    I need to be able to call a PyComponent's method from outside the scope of the App. I understand that app.cls gives the class that was used to instanciate the App, but it's not the actual instance, so I can't do something like app.cls.my_method(...).



    Is there a way to get the instance of the component inside the app wrapper, only knowing the App instance?



    Thanks!



    EDIT: After looking at the source, I found the mostly undocumented AppManager and Session definitions and could get a reference to the component's instance with:



    from flexx.app import manager
    app_instance = manager.get_connections('MyAppName')[0].app


    But if I call one of its methods from a watchdog.events.FileSystemEventHandler instantiated by the watchdog library, I get the following traceback:



     File "myfile.py", line 37, in on_created
    manager.get_connections('MyAppName')[0].app.update_verbose(False)
    File "libsite-packagesflexxevent_action.py", line 150, in __call__
    if loop.can_mutate(ob):
    File "libsite-packagesflexxevent_loop.py", line 85, in can_mutate
    active = self.get_active_component()
    File "libsite-packagesflexxevent_loop.py", line 103, in get_active_component
    if len(self._local._active_components) > 0:
    AttributeError: '_thread._local' object has no attribute '_active_components'


    Note that update_verbose is a Flexx action that mutates a property. I suspect an issue where the watchdog handler is running on a different thread but I can't see what to change...










    share|improve this question


























      0












      0








      0








      I'm currently diving into Flexx for making a UI to my Python program. I'm starting to get the hang of it but I'm running into a problem.



      I need to be able to call a PyComponent's method from outside the scope of the App. I understand that app.cls gives the class that was used to instanciate the App, but it's not the actual instance, so I can't do something like app.cls.my_method(...).



      Is there a way to get the instance of the component inside the app wrapper, only knowing the App instance?



      Thanks!



      EDIT: After looking at the source, I found the mostly undocumented AppManager and Session definitions and could get a reference to the component's instance with:



      from flexx.app import manager
      app_instance = manager.get_connections('MyAppName')[0].app


      But if I call one of its methods from a watchdog.events.FileSystemEventHandler instantiated by the watchdog library, I get the following traceback:



       File "myfile.py", line 37, in on_created
      manager.get_connections('MyAppName')[0].app.update_verbose(False)
      File "libsite-packagesflexxevent_action.py", line 150, in __call__
      if loop.can_mutate(ob):
      File "libsite-packagesflexxevent_loop.py", line 85, in can_mutate
      active = self.get_active_component()
      File "libsite-packagesflexxevent_loop.py", line 103, in get_active_component
      if len(self._local._active_components) > 0:
      AttributeError: '_thread._local' object has no attribute '_active_components'


      Note that update_verbose is a Flexx action that mutates a property. I suspect an issue where the watchdog handler is running on a different thread but I can't see what to change...










      share|improve this question
















      I'm currently diving into Flexx for making a UI to my Python program. I'm starting to get the hang of it but I'm running into a problem.



      I need to be able to call a PyComponent's method from outside the scope of the App. I understand that app.cls gives the class that was used to instanciate the App, but it's not the actual instance, so I can't do something like app.cls.my_method(...).



      Is there a way to get the instance of the component inside the app wrapper, only knowing the App instance?



      Thanks!



      EDIT: After looking at the source, I found the mostly undocumented AppManager and Session definitions and could get a reference to the component's instance with:



      from flexx.app import manager
      app_instance = manager.get_connections('MyAppName')[0].app


      But if I call one of its methods from a watchdog.events.FileSystemEventHandler instantiated by the watchdog library, I get the following traceback:



       File "myfile.py", line 37, in on_created
      manager.get_connections('MyAppName')[0].app.update_verbose(False)
      File "libsite-packagesflexxevent_action.py", line 150, in __call__
      if loop.can_mutate(ob):
      File "libsite-packagesflexxevent_loop.py", line 85, in can_mutate
      active = self.get_active_component()
      File "libsite-packagesflexxevent_loop.py", line 103, in get_active_component
      if len(self._local._active_components) > 0:
      AttributeError: '_thread._local' object has no attribute '_active_components'


      Note that update_verbose is a Flexx action that mutates a property. I suspect an issue where the watchdog handler is running on a different thread but I can't see what to change...







      python multithreading python-multithreading python-watchdog






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Mar 7 at 12:48







      beeb

















      asked Mar 6 at 16:27









      beebbeeb

      641526




      641526






















          1 Answer
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          0














          As suspected, the problem probably comes from the fact that the FileSystemEventHandler is running on a different thread than the Flexx loop. Thanks to the author almarklein for his help on solving this.



          The solution was to get a reference to the root object, not with the complicated method described above in my question, but rather with the return value from the launch call:



          root = app.launch('app')


          Then inside the event handler, tell the main loop to call my method (decorated with @flx.action):



          flx.loop.call_soon(root.my_action, 'argument`)


          Hope this helps someone some day!






          share|improve this answer
























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            1 Answer
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            active

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            active

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            active

            oldest

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            0














            As suspected, the problem probably comes from the fact that the FileSystemEventHandler is running on a different thread than the Flexx loop. Thanks to the author almarklein for his help on solving this.



            The solution was to get a reference to the root object, not with the complicated method described above in my question, but rather with the return value from the launch call:



            root = app.launch('app')


            Then inside the event handler, tell the main loop to call my method (decorated with @flx.action):



            flx.loop.call_soon(root.my_action, 'argument`)


            Hope this helps someone some day!






            share|improve this answer





























              0














              As suspected, the problem probably comes from the fact that the FileSystemEventHandler is running on a different thread than the Flexx loop. Thanks to the author almarklein for his help on solving this.



              The solution was to get a reference to the root object, not with the complicated method described above in my question, but rather with the return value from the launch call:



              root = app.launch('app')


              Then inside the event handler, tell the main loop to call my method (decorated with @flx.action):



              flx.loop.call_soon(root.my_action, 'argument`)


              Hope this helps someone some day!






              share|improve this answer



























                0












                0








                0







                As suspected, the problem probably comes from the fact that the FileSystemEventHandler is running on a different thread than the Flexx loop. Thanks to the author almarklein for his help on solving this.



                The solution was to get a reference to the root object, not with the complicated method described above in my question, but rather with the return value from the launch call:



                root = app.launch('app')


                Then inside the event handler, tell the main loop to call my method (decorated with @flx.action):



                flx.loop.call_soon(root.my_action, 'argument`)


                Hope this helps someone some day!






                share|improve this answer















                As suspected, the problem probably comes from the fact that the FileSystemEventHandler is running on a different thread than the Flexx loop. Thanks to the author almarklein for his help on solving this.



                The solution was to get a reference to the root object, not with the complicated method described above in my question, but rather with the return value from the launch call:



                root = app.launch('app')


                Then inside the event handler, tell the main loop to call my method (decorated with @flx.action):



                flx.loop.call_soon(root.my_action, 'argument`)


                Hope this helps someone some day!







                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Mar 7 at 14:29

























                answered Mar 7 at 14:13









                beebbeeb

                641526




                641526





























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