Restoring authorship annotation for <shadchin@yandex-team.ru>. Commit 2 of 2.

1 files changed, 401 insertions, 401 deletions

diff --git a/contrib/python/ipython/py3/IPython/external/qt_loaders.py b/contrib/python/ipython/py3/IPython/external/qt_loaders.py
index ee42ca6ffb..79805358e7 100644
--- a/contrib/python/ipython/py3/IPython/external/qt_loaders.py
+++ b/contrib/python/ipython/py3/IPython/external/qt_loaders.py
@@ -1,401 +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 
+"""
+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