"RuntimeError: Cannot change input buffer during execution" in console_widget.py

[mspacek]

Not sure what the sequence of events is, and I can't reproduce it reliably, but I've had this happen several times with ipython-qtconsole.

I type something, maybe a function name (say gca()), the call tip comes up, I hit ESC to clear it, then hit TAB to list the attribs, then ESC again, and so on. Maybe I plot something at some point, and then close it.

Sometimes, I get to the point where the cursor disappears, and the console doesn't respond to the keyboard. In my own app that embeds the (Rich)IPythonWidget, I can still access the menu and toolbar. Here's the associated error:

Traceback (most recent call last):
  File "/home/mspacek/source/ipython/IPython/frontend/qt/console/console_widget.py", line 225, in eventFilter
    return self._event_filter_console_keypress(event)
  File "/home/mspacek/source/ipython/IPython/frontend/qt/console/frontend_widget.py", line 270, in _event_filter_console_keypress
    return super(FrontendWidget, self)._event_filter_console_keypress(event)
  File "/home/mspacek/source/ipython/IPython/frontend/qt/console/console_widget.py", line 1041, in _event_filter_console_keypress
    self._keyboard_quit()
  File "/home/mspacek/source/ipython/IPython/frontend/qt/console/console_widget.py", line 1510, in _keyboard_quit
    self.input_buffer = ''
  File "/home/mspacek/source/ipython/IPython/frontend/qt/console/console_widget.py", line 490, in _set_input_buffer
    raise RuntimeError("Cannot change input buffer during execution.")
RuntimeError: Cannot change input buffer during execution.

I suppose this means the kernel is busy doing something it shouldn't be. Perhaps this is related to #499.

I have to close the console, and when I do, it seems to close cleanly. I'll try and reproduce this more reliably and report back.

[epatters]

Due to fixes I made a while ago (I can't find the commit), it is no longer possible for this exception to be raised.

Thanks for the report.