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Refuse to install event loop hooks when not using `prompt_toolkit` (#14132)...
Refuse to install event loop hooks when not using `prompt_toolkit` (#14132) Without this, `%gui` is effectively a no-op but the user thinks it works. For example. If running `ipython`: ``` In [1]: import matplotlib; matplotlib.use('QtAgg'); from matplotlib import pyplot; pyplot.ion(); pyplot.plot([1, 2, 3, 4]) Installed qt6 event loop hook. Out[1]: [<matplotlib.lines.Line2D at 0x1ba2f59d2a0>] ``` The window appears and responds as expected. If running `ipython --simple-prompt`, the user would see the same output, when in fact no event loop hook was installed since it's not supported without `prompt_toolkit`. The resulting Qt window is unresponsive because the event loop is not running, i.e. with `--simple-prompt`, Qt windows should block (but `pyplot` doesn't/can't know to do that) With this PR, the user will see: ``` In [1]: import matplotlib; matplotlib.use('QtAgg'); from matplotlib import pyplot; pyplot.ion(); pyplot.plot([1, 2, 3, 4]) Cannot install event loop hook for "qt" when running with `--simple-prompt`. NOTE: Tk is supported natively; use Tk apps and Tk backends with `--simple-prompt`. Out[1]: [<matplotlib.lines.Line2D at 0x170be0c0310>] ``` They'll still get an unresponsive Qt window, but they'll at least be told this can't work (while anything using Tk will work just fine).

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shimmodule.py
89 lines | 2.6 KiB | text/x-python | PythonLexer
"""A shim module for deprecated imports
"""
# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.
import importlib.abc
import importlib.util
import sys
import types
from importlib import import_module
from .importstring import import_item
class ShimWarning(Warning):
"""A warning to show when a module has moved, and a shim is in its place."""
class ShimImporter(importlib.abc.MetaPathFinder):
"""Import hook for a shim.
This ensures that submodule imports return the real target module,
not a clone that will confuse `is` and `isinstance` checks.
"""
def __init__(self, src, mirror):
self.src = src
self.mirror = mirror
def _mirror_name(self, fullname):
"""get the name of the mirrored module"""
return self.mirror + fullname[len(self.src) :]
def find_spec(self, fullname, path, target=None):
if fullname.startswith(self.src + "."):
mirror_name = self._mirror_name(fullname)
return importlib.util.find_spec(mirror_name)
class ShimModule(types.ModuleType):
def __init__(self, *args, **kwargs):
self._mirror = kwargs.pop("mirror")
src = kwargs.pop("src", None)
if src:
kwargs['name'] = src.rsplit('.', 1)[-1]
super(ShimModule, self).__init__(*args, **kwargs)
# add import hook for descendent modules
if src:
sys.meta_path.append(
ShimImporter(src=src, mirror=self._mirror)
)
@property
def __path__(self):
return []
@property
def __spec__(self):
"""Don't produce __spec__ until requested"""
return import_module(self._mirror).__spec__
def __dir__(self):
return dir(import_module(self._mirror))
@property
def __all__(self):
"""Ensure __all__ is always defined"""
mod = import_module(self._mirror)
try:
return mod.__all__
except AttributeError:
return [name for name in dir(mod) if not name.startswith('_')]
def __getattr__(self, key):
# Use the equivalent of import_item(name), see below
name = "%s.%s" % (self._mirror, key)
try:
return import_item(name)
except ImportError as e:
raise AttributeError(key) from e
def __repr__(self):
# repr on a module can be called during error handling; make sure
# it does not fail, even if the import fails
try:
return self.__getattr__("__repr__")()
except AttributeError:
return f"<ShimModule for {self._mirror!r}>"