Question

EDIT I isolated a real minimal example which does not work (it is a part of more complex code); the culprit is the inputhook part after all:

def foo():
    exec 'a=123' in globals()
    from IPython.frontend.terminal.embed import InteractiveShellEmbed
    ipshell=InteractiveShellEmbed()
    ipshell()

# without inputhook, 'a' is found just fine
import IPython.lib.inputhook
IPython.lib.inputhook.enable_gui(gui='qt4')

foo()

Running with 0.12:

In [1]: a
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
/tmp/<ipython-input-1-60b725f10c9c> in <module>()
----> 1 a

NameError: name 'a' is not defined

What would be the way around?

Answer 1

The problem is due to this call to InteractiveShell.instance() in the qt integration, when called before IPython is initialized. If this is called before your embedded shell is created, then some assumptions are not met. The fix is to create your embedded shell object first, then you shouldn’t have any issue. And you can retrieve the same object from anywhere else in your code by simply calling InteractiveShellEmbed.instance().

This version should work just fine, by creating the InteractiveShellEmbed instance first:

from IPython.frontend.terminal.embed import InteractiveShellEmbed
# create ipshell *before* calling enable_gui
# it is important that you use instance(), instead of the class
# constructor, so that it creates the global InteractiveShell singleton
ipshell = InteractiveShellEmbed.instance()

import IPython.lib.inputhook
IPython.lib.inputhook.enable_gui(gui='tk')

def foo():
    # without inputhook, 'a' is found just fine
    exec 'a=123' in globals()
    # all calls to instance() will always return the same object
    ipshell = InteractiveShellEmbed.instance()
    ipshell()

foo()