make basic execution path jupyter-agnostic by inheriting InteractiveShell

[smacke]

make basic execution path jupyter-agnostic by inheriting InteractiveShell

[smacke]

To create IPyflow variants of all the various subclasses of InteractiveShell, it seems like the cleanest way (but definitely not the easiest to understand) is to do fancy metaclass stuff to patch IPyflowInteractiveShell into the mro. Toy example:

from IPython.terminal.embed import InteractiveShellEmbed
from IPython.terminal.interactiveshell import InteractiveShell
from traitlets import MetaHasTraits


def make_mro_inserter_metaclass(old_class, new_class):
    class MetaMroInserter(MetaHasTraits):
        def mro(cls):
            ret = []
            for clazz in super().mro():
                if clazz is old_class:
                    ret.append(new_class)
                ret.append(clazz)
            return ret
    return MetaMroInserter


class MyInteractiveShell(InteractiveShell):
    def run_cell(self, *args, **kwargs):
        print("run cell")
        return super().run_cell(*args, **kwargs)


class MyInteractiveShellEmbed(InteractiveShellEmbed, metaclass=make_mro_inserter_metaclass(InteractiveShell, MyInteractiveShell)):
    pass

ipshell = MyInteractiveShellEmbed()
ipshell.run_cell("x = 0")  # prints 'run cell' before running the cell

[smacke]

This would more readily unblock use cases like #134.