added QT_API_DEFAULT Qt option. Fixed reversed MPL qt logic test.

IPython/external/qt_for_kernel.py

@@ -1,84 +1,84 b''
 """ Import Qt in a manner suitable for an IPython kernel.
 
 This is the import used for the `gui=qt` or `pylab=qt` initialization.
 
 Import Priority:
 
 if Qt4 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 ETS' QT_API env variable
 
 if QT_API not set:
     ask matplotlib via rcParams['backend.qt4']
     if it said PyQt:
         use PyQt4 @v1
     elif it said PySide:
         use PySide
 
     else: (matplotlib said nothing)
         # this is the default path - nobody told us anything
         try:
             PyQt @v1
         except:
             fallback on PySide
 else:
     use PyQt @v2 or PySide, depending on QT_API
     because ETS doesn't work with PyQt @v1.
 
 """
 
 import os
 import sys
 
 from IPython.utils.warn import warn
 from IPython.utils.version import check_version
 from IPython.external.qt_loaders import (load_qt, QT_API_PYSIDE,
-                                         QT_API_PYQT, QT_API_PYQTv1,
+                                         QT_API_PYQT, QT_API_PYQT_DEFAULT,
                                          loaded_api)
 
 #Constraints placed on an imported matplotlib
 def matplotlib_options(mpl):
     if mpl is None:
         return
     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_PYQTv1]
+        return [QT_API_PYQT_DEFAULT]
     raise ImportError("unhandled value for backend.qt4 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 check_version(mpl.__version__, '1.0.2'):
+    if mpl is not None and not check_version(mpl.__version__, '1.0.2'):
         #1.0.1 only supports PyQt4 v1
-        return [QT_API_PYQTv1]
+        return [QT_API_PYQT_DEFAULT]
 
     if os.environ.get('QT_API', None) is None:
         #no ETS variable. Ask mpl, then use either
-        return matplotlib_options(mpl) or [QT_API_PYQTv1, QT_API_PYSIDE]
+        return matplotlib_options(mpl) or [QT_API_PYQT_DEFAULT, QT_API_PYSIDE]
 
     #ETS variable present. Will fallback to external.qt
     return None
 
 api_opts = get_options()
 if api_opts is not None:
     QtCore, QtGui, QtSvg, QT_API = load_qt(api_opts)
 
 else: # use ETS variable
     from IPython.external.qt import QtCore, QtGui, QtSvg, QT_API

IPython/external/qt_loaders.py

@@ -1,238 +1,258 b''
 """
 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
 from functools import partial
 
 from IPython.utils.version import check_version
 
 # Available APIs.
 QT_API_PYQT = 'pyqt'
 QT_API_PYQTv1 = 'pyqtv1'
+QT_API_PYQT_DEFAULT = 'pyqtdefault' # don't set SIP explicitly
 QT_API_PYSIDE = 'pyside'
 
 
 class ImportDenier(object):
     """Import Hook that will guard against bad Qt imports
     once IPython commits to a specific binding
     """
-    __forbidden = set()
 
     def __init__(self):
         self.__forbidden = None
 
     def forbid(self, module_name):
         sys.modules.pop(module_name, None)
         self.__forbidden = module_name
 
     def find_module(self, mod_name, pth):
         if pth:
             return
         if mod_name == self.__forbidden:
             return self
 
     def load_module(self, mod_name):
         raise ImportError("""
     Importing %s disabled by IPython, which has
     already imported an Incompatible QT Binding: %s
     """ % (mod_name, loaded_api()))
 
 ID = ImportDenier()
 sys.meta_path.append(ID)
 
 
 def commit_api(api):
     """Commit to a particular API, and trigger ImportErrors on subsequent
        dangerous imports"""
 
     if api == QT_API_PYSIDE:
         ID.forbid('PyQt4')
     else:
         ID.forbid('PySide')
 
 
 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, 'pyside', 'pyqt', or 'pyqtv1'
     """
     if 'PyQt4.QtCore' in sys.modules:
         if qtapi_version() == 2:
             return QT_API_PYQT
         else:
             return QT_API_PYQTv1
     elif 'PySide.QtCore' in sys.modules:
         return QT_API_PYSIDE
     return None
 
 
 def has_binding(api):
     """Safely check for PyQt4 or PySide, without importing
        submodules
 
        Parameters
        ----------
-       api : str [ 'pyqtv1' | 'pyqt' | 'pyside']
+       api : str [ 'pyqtv1' | 'pyqt' | 'pyside' | 'pyqtdefault']
             Which module to check for
 
        Returns
        -------
        True if the relevant module appears to be importable
     """
     # we can't import an incomplete pyside and pyqt4
     # this will cause a crash in sip (#1431)
     # check for complete presence before importing
     module_name = {QT_API_PYSIDE: 'PySide',
                    QT_API_PYQT: 'PyQt4',
-                   QT_API_PYQTv1: 'PyQt4'}
+                   QT_API_PYQTv1: 'PyQt4',
+                   QT_API_PYQT_DEFAULT: 'PyQt4'}
     module_name = module_name[api]
 
     import imp
     try:
         #importing top level PyQt4/PySide module is ok...
         mod = __import__(module_name)
         #...importing submodules is not
         imp.find_module('QtCore', mod.__path__)
         imp.find_module('QtGui', mod.__path__)
         imp.find_module('QtSvg', mod.__path__)
 
         #we can also safely check PySide version
         if api == QT_API_PYSIDE:
             return check_version(mod.__version__, '1.0.3')
         else:
             return True
     except ImportError:
         return False
 
 
 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:
         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()
-    return has_binding(api) and current in [api, None]
+    if api == QT_API_PYQT_DEFAULT:
+        return current in [QT_API_PYQT, QT_API_PYQTv1, 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
-    sip.setapi('QString', version)
-    sip.setapi('QVariant', version)
+
+    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_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 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',
         'pyqt', and 'pyqtv1'
 
     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 becaues they aren't installed, or because
     an incompatible library has already been installed)
     """
     loaders = {QT_API_PYSIDE: import_pyside,
                QT_API_PYQT: import_pyqt4,
-               QT_API_PYQTv1: partial(import_pyqt4, version=1)
+               QT_API_PYQTv1: partial(import_pyqt4, version=1),
+               QT_API_PYQT_DEFAULT: partial(import_pyqt4, version=None)
                }
 
     for api in api_options:
 
         if api not in loaders:
             raise RuntimeError(
-                "Invalid Qt API %r, valid values are: %r, %r, %r" %
-                (api, QT_API_PYSIDE, QT_API_PYQT, QT_API_PYQTv1))
+                "Invalid Qt API %r, valid values are: %r, %r, %r, %r" %
+                (api, QT_API_PYSIDE, QT_API_PYQT,
+                 QT_API_PYQTv1, QT_API_PYQT_DEFAULT))
 
         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 or PySide >= 1.0.3 is available,
     and only one is imported per session.
 
     Currently-imported Qt library:   %r
     PyQt4 installed:                 %s
     PySide >= 1.0.3 installed:       %s
     Tried to load:                   %r
     """ % (loaded_api(),
            has_binding(QT_API_PYQT),
            has_binding(QT_API_PYSIDE),
            api_options))