intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

7 files changed, 740 insertions, 0 deletions

diff --git a/contrib/python/ipython/py3/IPython/external/__init__.py b/contrib/python/ipython/py3/IPython/external/__init__.py
new file mode 100644
index 00000000000..1c8c546f118
--- /dev/null
+++ b/contrib/python/ipython/py3/IPython/external/__init__.py
@@ -0,0 +1,5 @@
+"""
+This package contains all third-party modules bundled with IPython.
+"""
+
+__all__ = []
diff --git a/contrib/python/ipython/py3/IPython/external/decorators/__init__.py b/contrib/python/ipython/py3/IPython/external/decorators/__init__.py
new file mode 100644
index 00000000000..1db80edd357
--- /dev/null
+++ b/contrib/python/ipython/py3/IPython/external/decorators/__init__.py
@@ -0,0 +1,8 @@
+try:
+    from numpy.testing import KnownFailure, knownfailureif
+except ImportError:
+    from ._decorators import knownfailureif
+    try:
+        from ._numpy_testing_noseclasses import KnownFailure
+    except ImportError:
+        pass
diff --git a/contrib/python/ipython/py3/IPython/external/decorators/_decorators.py b/contrib/python/ipython/py3/IPython/external/decorators/_decorators.py
new file mode 100644
index 00000000000..18f847adadd
--- /dev/null
+++ b/contrib/python/ipython/py3/IPython/external/decorators/_decorators.py
@@ -0,0 +1,143 @@
+"""
+Decorators for labeling and modifying behavior of test objects.
+
+Decorators that merely return a modified version of the original
+function object are straightforward. Decorators that return a new
+function object need to use
+::
+
+  nose.tools.make_decorator(original_function)(decorator)
+
+in returning the decorator, in order to preserve meta-data such as
+function name, setup and teardown functions and so on - see
+``nose.tools`` for more information.
+
+"""
+
+# IPython changes: make this work if numpy not available
+# Original code:
+try:
+    from ._numpy_testing_noseclasses import KnownFailureTest
+except:
+    pass
+
+# End IPython changes
+
+
+def skipif(skip_condition, msg=None):
+    """
+    Make function raise SkipTest exception if a given condition is true.
+
+    If the condition is a callable, it is used at runtime to dynamically
+    make the decision. This is useful for tests that may require costly
+    imports, to delay the cost until the test suite is actually executed.
+
+    Parameters
+    ----------
+    skip_condition : bool or callable
+        Flag to determine whether to skip the decorated test.
+    msg : str, optional
+        Message to give on raising a SkipTest exception. Default is None.
+
+    Returns
+    -------
+    decorator : function
+        Decorator which, when applied to a function, causes SkipTest
+        to be raised when `skip_condition` is True, and the function
+        to be called normally otherwise.
+
+    Notes
+    -----
+    The decorator itself is decorated with the ``nose.tools.make_decorator``
+    function in order to transmit function name, and various other metadata.
+
+    """
+
+    def skip_decorator(f):
+        # Local import to avoid a hard nose dependency and only incur the
+        # import time overhead at actual test-time.
+        import nose
+
+        # Allow for both boolean or callable skip conditions.
+        if callable(skip_condition):
+            skip_val = lambda : skip_condition()
+        else:
+            skip_val = lambda : skip_condition
+
+        def get_msg(func,msg=None):
+            """Skip message with information about function being skipped."""
+            if msg is None:
+                out = 'Test skipped due to test condition'
+            else:
+                out = '\n'+msg
+
+            return "Skipping test: %s%s" % (func.__name__,out)
+
+        # We need to define *two* skippers because Python doesn't allow both
+        # return with value and yield inside the same function.
+        def skipper_func(*args, **kwargs):
+            """Skipper for normal test functions."""
+            if skip_val():
+                raise nose.SkipTest(get_msg(f,msg))
+            else:
+                return f(*args, **kwargs)
+
+        def skipper_gen(*args, **kwargs):
+            """Skipper for test generators."""
+            if skip_val():
+                raise nose.SkipTest(get_msg(f,msg))
+            else:
+                for x in f(*args, **kwargs):
+                    yield x
+
+        # Choose the right skipper to use when building the actual decorator.
+        if nose.util.isgenerator(f):
+            skipper = skipper_gen
+        else:
+            skipper = skipper_func
+
+        return nose.tools.make_decorator(f)(skipper)
+
+    return skip_decorator
+
+def knownfailureif(fail_condition, msg=None):
+    """
+    Make function raise KnownFailureTest exception if given condition is true.
+
+    Parameters
+    ----------
+    fail_condition : bool
+        Flag to determine whether to mark the decorated test as a known
+        failure (if True) or not (if False).
+    msg : str, optional
+        Message to give on raising a KnownFailureTest exception.
+        Default is None.
+
+    Returns
+    -------
+    decorator : function
+        Decorator, which, when applied to a function, causes KnownFailureTest to
+        be raised when `fail_condition` is True and the test fails.
+
+    Notes
+    -----
+    The decorator itself is decorated with the ``nose.tools.make_decorator``
+    function in order to transmit function name, and various other metadata.
+
+    """
+    if msg is None:
+        msg = 'Test skipped due to known failure'
+
+    def knownfail_decorator(f):
+        # Local import to avoid a hard nose dependency and only incur the
+        # import time overhead at actual test-time.
+        import nose
+
+        def knownfailer(*args, **kwargs):
+            if fail_condition:
+                raise KnownFailureTest(msg)
+            else:
+                return f(*args, **kwargs)
+        return nose.tools.make_decorator(f)(knownfailer)
+
+    return knownfail_decorator
diff --git a/contrib/python/ipython/py3/IPython/external/decorators/_numpy_testing_noseclasses.py b/contrib/python/ipython/py3/IPython/external/decorators/_numpy_testing_noseclasses.py
new file mode 100644
index 00000000000..ca6ccd87bbc
--- /dev/null
+++ b/contrib/python/ipython/py3/IPython/external/decorators/_numpy_testing_noseclasses.py
@@ -0,0 +1,41 @@
+# IPython: modified copy of numpy.testing.noseclasses, so
+# IPython.external._decorators works without numpy being installed.
+
+# These classes implement a "known failure" error class.
+
+import os
+
+from nose.plugins.errorclass import ErrorClass, ErrorClassPlugin
+
+class KnownFailureTest(Exception):
+    '''Raise this exception to mark a test as a known failing test.'''
+    pass
+
+
+class KnownFailure(ErrorClassPlugin):
+    '''Plugin that installs a KNOWNFAIL error class for the
+    KnownFailureClass exception.  When KnownFailureTest is raised,
+    the exception will be logged in the knownfail attribute of the
+    result, 'K' or 'KNOWNFAIL' (verbose) will be output, and the
+    exception will not be counted as an error or failure.'''
+    enabled = True
+    knownfail = ErrorClass(KnownFailureTest,
+                           label='KNOWNFAIL',
+                           isfailure=False)
+
+    def options(self, parser, env=os.environ):
+        env_opt = 'NOSE_WITHOUT_KNOWNFAIL'
+        parser.add_option('--no-knownfail', action='store_true',
+                          dest='noKnownFail', default=env.get(env_opt, False),
+                          help='Disable special handling of KnownFailureTest '
+                               'exceptions')
+
+    def configure(self, options, conf):
+        if not self.can_configure:
+            return
+        self.conf = conf
+        disable = getattr(options, 'noKnownFail', False)
+        if disable:
+            self.enabled = False
+
+
diff --git a/contrib/python/ipython/py3/IPython/external/mathjax.py b/contrib/python/ipython/py3/IPython/external/mathjax.py
new file mode 100644
index 00000000000..1b9b80905ba
--- /dev/null
+++ b/contrib/python/ipython/py3/IPython/external/mathjax.py
@@ -0,0 +1,13 @@
+#!/usr/bin/python
+"""
+`IPython.external.mathjax` is deprecated with IPython 4.0+
+
+mathjax is now install by default with the notebook package
+
+"""
+
+import sys 
+
+if __name__ == '__main__' :
+    sys.exit("IPython.external.mathjax is deprecated, Mathjax is now installed by default with the notebook package")
+
diff --git a/contrib/python/ipython/py3/IPython/external/qt_for_kernel.py b/contrib/python/ipython/py3/IPython/external/qt_for_kernel.py
new file mode 100644
index 00000000000..d2e7bd99f01
--- /dev/null
+++ b/contrib/python/ipython/py3/IPython/external/qt_for_kernel.py
@@ -0,0 +1,129 @@
+""" Import Qt in a manner suitable for an IPython kernel.
+
+This is the import used for the `gui=qt` or `matplotlib=qt` initialization.
+
+Import Priority:
+
+if Qt has been imported anywhere else:
+   use that
+
+if matplotlib has been imported and doesn't support v2 (<= 1.0.1):
+    use PyQt4 @v1
+
+Next, ask QT_API env variable
+
+if QT_API not set:
+    ask matplotlib what it's using. If Qt4Agg or Qt5Agg, then use the
+        version matplotlib is configured with
+
+    else: (matplotlib said nothing)
+        # this is the default path - nobody told us anything
+        try in this order:
+            PyQt default version, PySide, PyQt5
+else:
+    use what QT_API says
+
+"""
+# NOTE: This is no longer an external, third-party module, and should be
+# considered part of IPython. For compatibility however, it is being kept in
+# IPython/external.
+
+import os
+import sys
+
+from IPython.utils.version import check_version
+from IPython.external.qt_loaders import (
+    load_qt,
+    loaded_api,
+    enum_factory,
+    # QT6
+    QT_API_PYQT6,
+    QT_API_PYSIDE6,
+    # QT5
+    QT_API_PYQT5,
+    QT_API_PYSIDE2,
+    # QT4
+    QT_API_PYQTv1,
+    QT_API_PYQT,
+    QT_API_PYSIDE,
+    # default
+    QT_API_PYQT_DEFAULT,
+)
+
+_qt_apis = (
+    # QT6
+    QT_API_PYQT6,
+    QT_API_PYSIDE6,
+    # QT5
+    QT_API_PYQT5,
+    QT_API_PYSIDE2,
+    # QT4
+    QT_API_PYQTv1,
+    QT_API_PYQT,
+    QT_API_PYSIDE,
+    # default
+    QT_API_PYQT_DEFAULT,
+)
+
+
+def matplotlib_options(mpl):
+    """Constraints placed on an imported matplotlib."""
+    if mpl is None:
+        return
+    backend = mpl.rcParams.get('backend', None)
+    if backend == 'Qt4Agg':
+        mpqt = mpl.rcParams.get('backend.qt4', None)
+        if mpqt is None:
+            return None
+        if mpqt.lower() == 'pyside':
+            return [QT_API_PYSIDE]
+        elif mpqt.lower() == 'pyqt4':
+            return [QT_API_PYQT_DEFAULT]
+        elif mpqt.lower() == 'pyqt4v2':
+            return [QT_API_PYQT]
+        raise ImportError("unhandled value for backend.qt4 from matplotlib: %r" %
+                          mpqt)
+    elif backend == 'Qt5Agg':
+        mpqt = mpl.rcParams.get('backend.qt5', None)
+        if mpqt is None:
+            return None
+        if mpqt.lower() == 'pyqt5':
+            return [QT_API_PYQT5]
+        raise ImportError("unhandled value for backend.qt5 from matplotlib: %r" %
+                          mpqt)
+
+def get_options():
+    """Return a list of acceptable QT APIs, in decreasing order of preference."""
+    #already imported Qt somewhere. Use that
+    loaded = loaded_api()
+    if loaded is not None:
+        return [loaded]
+
+    mpl = sys.modules.get('matplotlib', None)
+
+    if mpl is not None and not check_version(mpl.__version__, '1.0.2'):
+        #1.0.1 only supports PyQt4 v1
+        return [QT_API_PYQT_DEFAULT]
+
+    qt_api = os.environ.get('QT_API', None)
+    if qt_api is None:
+        #no ETS variable. Ask mpl, then use default fallback path
+        return matplotlib_options(mpl) or [
+            QT_API_PYQT_DEFAULT,
+            QT_API_PYQT6,
+            QT_API_PYSIDE6,
+            QT_API_PYQT5,
+            QT_API_PYSIDE2,
+            QT_API_PYQT,
+            QT_API_PYSIDE,
+        ]
+    elif qt_api not in _qt_apis:
+        raise RuntimeError("Invalid Qt API %r, valid values are: %r" %
+                           (qt_api, ', '.join(_qt_apis)))
+    else:
+        return [qt_api]
+
+
+api_opts = get_options()
+QtCore, QtGui, QtSvg, QT_API = load_qt(api_opts)
+enum_helper = enum_factory(QT_API, QtCore)
diff --git a/contrib/python/ipython/py3/IPython/external/qt_loaders.py b/contrib/python/ipython/py3/IPython/external/qt_loaders.py
new file mode 100644
index 00000000000..79805358e72
--- /dev/null
+++ b/contrib/python/ipython/py3/IPython/external/qt_loaders.py
@@ -0,0 +1,401 @@
+"""
+This module contains factory functions that attempt
+to return Qt submodules from the various python Qt bindings.
+
+It also protects against double-importing Qt with different
+bindings, which is unstable and likely to crash
+
+This is used primarily by qt and qt_for_kernel, and shouldn't
+be accessed directly from the outside
+"""
+import sys
+import types
+from functools import partial, lru_cache
+import operator
+
+from IPython.utils.version import check_version
+
+# ### Available APIs.
+# Qt6
+QT_API_PYQT6 = "pyqt6"
+QT_API_PYSIDE6 = "pyside6"
+
+# Qt5
+QT_API_PYQT5 = 'pyqt5'
+QT_API_PYSIDE2 = 'pyside2'
+
+# Qt4
+QT_API_PYQT = "pyqt"  # Force version 2
+QT_API_PYQTv1 = "pyqtv1"  # Force version 2
+QT_API_PYSIDE = "pyside"
+
+QT_API_PYQT_DEFAULT = "pyqtdefault"  # use system default for version 1 vs. 2
+
+api_to_module = {
+    # Qt6
+    QT_API_PYQT6: "PyQt6",
+    QT_API_PYSIDE6: "PySide6",
+    # Qt5
+    QT_API_PYQT5: "PyQt5",
+    QT_API_PYSIDE2: "PySide2",
+    # Qt4
+    QT_API_PYSIDE: "PySide",
+    QT_API_PYQT: "PyQt4",
+    QT_API_PYQTv1: "PyQt4",
+    # default
+    QT_API_PYQT_DEFAULT: "PyQt6",
+}
+
+
+class ImportDenier(object):
+    """Import Hook that will guard against bad Qt imports
+    once IPython commits to a specific binding
+    """
+
+    def __init__(self):
+        self.__forbidden = set()
+
+    def forbid(self, module_name):
+        sys.modules.pop(module_name, None)
+        self.__forbidden.add(module_name)
+
+    def find_module(self, fullname, path=None):
+        if path:
+            return
+        if fullname in self.__forbidden:
+            return self
+
+    def load_module(self, fullname):
+        raise ImportError("""
+    Importing %s disabled by IPython, which has
+    already imported an Incompatible QT Binding: %s
+    """ % (fullname, loaded_api()))
+
+
+ID = ImportDenier()
+sys.meta_path.insert(0, ID)
+
+
+def commit_api(api):
+    """Commit to a particular API, and trigger ImportErrors on subsequent
+       dangerous imports"""
+    modules = set(api_to_module.values())
+
+    modules.remove(api_to_module[api])
+    for mod in modules:
+        ID.forbid(mod)
+
+
+def loaded_api():
+    """Return which API is loaded, if any
+
+    If this returns anything besides None,
+    importing any other Qt binding is unsafe.
+
+    Returns
+    -------
+    None, 'pyside6', 'pyqt6', 'pyside2', 'pyside', 'pyqt', 'pyqt5', 'pyqtv1'
+    """
+    if sys.modules.get("PyQt6.QtCore"):
+        return QT_API_PYQT6
+    elif sys.modules.get("PySide6.QtCore"):
+        return QT_API_PYSIDE6
+    elif sys.modules.get("PyQt5.QtCore"):
+        return QT_API_PYQT5
+    elif sys.modules.get("PySide2.QtCore"):
+        return QT_API_PYSIDE2
+    elif sys.modules.get("PyQt4.QtCore"):
+        if qtapi_version() == 2:
+            return QT_API_PYQT
+        else:
+            return QT_API_PYQTv1
+    elif sys.modules.get("PySide.QtCore"):
+        return QT_API_PYSIDE
+
+    return None
+
+
+def has_binding(api):
+    """Safely check for PyQt4/5, PySide or PySide2, without importing submodules
+
+        Parameters
+        ----------
+        api : str [ 'pyqtv1' | 'pyqt' | 'pyqt5' | 'pyside' | 'pyside2' | 'pyqtdefault']
+             Which module to check for
+
+        Returns
+        -------
+        True if the relevant module appears to be importable
+     """
+    module_name = api_to_module[api]
+    from importlib.util import find_spec
+
+    required = ['QtCore', 'QtGui', 'QtSvg']
+    if api in (QT_API_PYQT5, QT_API_PYSIDE2, QT_API_PYQT6, QT_API_PYSIDE6):
+        # QT5 requires QtWidgets too
+        required.append('QtWidgets')
+
+    for submod in required:
+        try:
+            spec = find_spec('%s.%s' % (module_name, submod))
+        except ImportError:
+            # Package (e.g. PyQt5) not found
+            return False
+        else:
+            if spec is None:
+                # Submodule (e.g. PyQt5.QtCore) not found
+                return False
+
+    if api == QT_API_PYSIDE:
+        # We can also safely check PySide version
+        import PySide
+        return check_version(PySide.__version__, '1.0.3')
+
+    return True
+
+
+def qtapi_version():
+    """Return which QString API has been set, if any
+
+    Returns
+    -------
+    The QString API version (1 or 2), or None if not set
+    """
+    try:
+        import sip
+    except ImportError:
+        # as of PyQt5 5.11, sip is no longer available as a top-level
+        # module and needs to be imported from the PyQt5 namespace
+        try:
+            from PyQt5 import sip
+        except ImportError:
+            return
+    try:
+        return sip.getapi('QString')
+    except ValueError:
+        return
+
+
+def can_import(api):
+    """Safely query whether an API is importable, without importing it"""
+    if not has_binding(api):
+        return False
+
+    current = loaded_api()
+    if api == QT_API_PYQT_DEFAULT:
+        return current in [QT_API_PYQT6, None]
+    else:
+        return current in [api, None]
+
+
+def import_pyqt4(version=2):
+    """
+    Import PyQt4
+
+    Parameters
+    ----------
+    version : 1, 2, or None
+      Which QString/QVariant API to use. Set to None to use the system
+      default
+
+    ImportErrors rasied within this function are non-recoverable
+    """
+    # The new-style string API (version=2) automatically
+    # converts QStrings to Unicode Python strings. Also, automatically unpacks
+    # QVariants to their underlying objects.
+    import sip
+
+    if version is not None:
+        sip.setapi('QString', version)
+        sip.setapi('QVariant', version)
+
+    from PyQt4 import QtGui, QtCore, QtSvg
+
+    if not check_version(QtCore.PYQT_VERSION_STR, '4.7'):
+        raise ImportError("IPython requires PyQt4 >= 4.7, found %s" %
+                          QtCore.PYQT_VERSION_STR)
+
+    # Alias PyQt-specific functions for PySide compatibility.
+    QtCore.Signal = QtCore.pyqtSignal
+    QtCore.Slot = QtCore.pyqtSlot
+
+    # query for the API version (in case version == None)
+    version = sip.getapi('QString')
+    api = QT_API_PYQTv1 if version == 1 else QT_API_PYQT
+    return QtCore, QtGui, QtSvg, api
+
+
+def import_pyqt5():
+    """
+    Import PyQt5
+
+    ImportErrors rasied within this function are non-recoverable
+    """
+
+    from PyQt5 import QtCore, QtSvg, QtWidgets, QtGui
+
+    # Alias PyQt-specific functions for PySide compatibility.
+    QtCore.Signal = QtCore.pyqtSignal
+    QtCore.Slot = QtCore.pyqtSlot
+
+    # Join QtGui and QtWidgets for Qt4 compatibility.
+    QtGuiCompat = types.ModuleType('QtGuiCompat')
+    QtGuiCompat.__dict__.update(QtGui.__dict__)
+    QtGuiCompat.__dict__.update(QtWidgets.__dict__)
+
+    api = QT_API_PYQT5
+    return QtCore, QtGuiCompat, QtSvg, api
+
+
+def import_pyqt6():
+    """
+    Import PyQt6
+
+    ImportErrors rasied within this function are non-recoverable
+    """
+
+    from PyQt6 import QtCore, QtSvg, QtWidgets, QtGui
+
+    # Alias PyQt-specific functions for PySide compatibility.
+    QtCore.Signal = QtCore.pyqtSignal
+    QtCore.Slot = QtCore.pyqtSlot
+
+    # Join QtGui and QtWidgets for Qt4 compatibility.
+    QtGuiCompat = types.ModuleType("QtGuiCompat")
+    QtGuiCompat.__dict__.update(QtGui.__dict__)
+    QtGuiCompat.__dict__.update(QtWidgets.__dict__)
+
+    api = QT_API_PYQT6
+    return QtCore, QtGuiCompat, QtSvg, api
+
+
+def import_pyside():
+    """
+    Import PySide
+
+    ImportErrors raised within this function are non-recoverable
+    """
+    from PySide import QtGui, QtCore, QtSvg
+    return QtCore, QtGui, QtSvg, QT_API_PYSIDE
+
+def import_pyside2():
+    """
+    Import PySide2
+
+    ImportErrors raised within this function are non-recoverable
+    """
+    from PySide2 import QtGui, QtCore, QtSvg, QtWidgets, QtPrintSupport
+
+    # Join QtGui and QtWidgets for Qt4 compatibility.
+    QtGuiCompat = types.ModuleType('QtGuiCompat')
+    QtGuiCompat.__dict__.update(QtGui.__dict__)
+    QtGuiCompat.__dict__.update(QtWidgets.__dict__)
+    QtGuiCompat.__dict__.update(QtPrintSupport.__dict__)
+
+    return QtCore, QtGuiCompat, QtSvg, QT_API_PYSIDE2
+
+
+def import_pyside6():
+    """
+    Import PySide6
+
+    ImportErrors raised within this function are non-recoverable
+    """
+    from PySide6 import QtGui, QtCore, QtSvg, QtWidgets, QtPrintSupport
+
+    # Join QtGui and QtWidgets for Qt4 compatibility.
+    QtGuiCompat = types.ModuleType("QtGuiCompat")
+    QtGuiCompat.__dict__.update(QtGui.__dict__)
+    QtGuiCompat.__dict__.update(QtWidgets.__dict__)
+    QtGuiCompat.__dict__.update(QtPrintSupport.__dict__)
+
+    return QtCore, QtGuiCompat, QtSvg, QT_API_PYSIDE6
+
+
+def load_qt(api_options):
+    """
+    Attempt to import Qt, given a preference list
+    of permissible bindings
+
+    It is safe to call this function multiple times.
+
+    Parameters
+    ----------
+    api_options: List of strings
+        The order of APIs to try. Valid items are 'pyside', 'pyside2',
+        'pyqt', 'pyqt5', 'pyqtv1' and 'pyqtdefault'
+
+    Returns
+    -------
+
+    A tuple of QtCore, QtGui, QtSvg, QT_API
+    The first three are the Qt modules. The last is the
+    string indicating which module was loaded.
+
+    Raises
+    ------
+    ImportError, if it isn't possible to import any requested
+    bindings (either because they aren't installed, or because
+    an incompatible library has already been installed)
+    """
+    loaders = {
+        # Qt6
+        QT_API_PYQT6: import_pyqt6,
+        QT_API_PYSIDE6: import_pyside6,
+        # Qt5
+        QT_API_PYQT5: import_pyqt5,
+        QT_API_PYSIDE2: import_pyside2,
+        # Qt4
+        QT_API_PYSIDE: import_pyside,
+        QT_API_PYQT: import_pyqt4,
+        QT_API_PYQTv1: partial(import_pyqt4, version=1),
+        # default
+        QT_API_PYQT_DEFAULT: import_pyqt6,
+    }
+
+    for api in api_options:
+
+        if api not in loaders:
+            raise RuntimeError(
+                "Invalid Qt API %r, valid values are: %s" %
+                (api, ", ".join(["%r" % k for k in loaders.keys()])))
+
+        if not can_import(api):
+            continue
+
+        #cannot safely recover from an ImportError during this
+        result = loaders[api]()
+        api = result[-1]  # changed if api = QT_API_PYQT_DEFAULT
+        commit_api(api)
+        return result
+    else:
+        raise ImportError("""
+    Could not load requested Qt binding. Please ensure that
+    PyQt4 >= 4.7, PyQt5, PySide >= 1.0.3 or PySide2 is available,
+    and only one is imported per session.
+
+    Currently-imported Qt library:                              %r
+    PyQt4 available (requires QtCore, QtGui, QtSvg):            %s
+    PyQt5 available (requires QtCore, QtGui, QtSvg, QtWidgets): %s
+    PySide >= 1.0.3 installed:                                  %s
+    PySide2 installed:                                          %s
+    Tried to load:                                              %r
+    """ % (loaded_api(),
+           has_binding(QT_API_PYQT),
+           has_binding(QT_API_PYQT5),
+           has_binding(QT_API_PYSIDE),
+           has_binding(QT_API_PYSIDE2),
+           api_options))
+
+
+def enum_factory(QT_API, QtCore):
+    """Construct an enum helper to account for PyQt5 <-> PyQt6 changes."""
+
+    @lru_cache(None)
+    def _enum(name):
+        # foo.bar.Enum.Entry (PyQt6) <=> foo.bar.Entry (non-PyQt6).
+        return operator.attrgetter(
+            name if QT_API == QT_API_PYQT6 else name.rpartition(".")[0]
+        )(sys.modules[QtCore.__package__])
+
+    return _enum