FIX: be more careful about pyside

tacaswell · tacaswell · commit cdc52bfecb95 · 2015-10-06T01:00:36.000-04:00
If:

 1. backend is not Qt{4,5}Agg
 2. PyQt4 and PySide are installed, PyQt5 is not
 3. backend.qt4 == 'PySide'

The fall through will start trying to import PyQt5 (so sip will be
imported as it is installed for PyQt4).  It will then fall back to Qt4
using the binding specified in the rcparam ('PySide') which will then
miss the qt4 import conditionals which means QtCore is never imported
which means we get name errors from the pyqt / pyside patch up code.

This catches those exceptions and gives pyside a chance to be imported.
diff --git a/lib/matplotlib/backends/qt_compat.py b/lib/matplotlib/backends/qt_compat.py
@@ -139,19 +139,22 @@ def _getSaveFileName(*args, **kwargs):
             # call to getapi() can fail in older versions of sip
             def _getSaveFileName(*args, **kwargs):
                 return QtGui.QFileDialog.getSaveFileName(*args, **kwargs), None
-
-    # Alias PyQt-specific functions for PySide compatibility.
-    QtCore.Signal = QtCore.pyqtSignal
     try:
-        QtCore.Slot = QtCore.pyqtSlot
-    except AttributeError:
-        # Not a perfect match but works in simple cases
-        QtCore.Slot = QtCore.pyqtSignature
-
-    QtCore.Property = QtCore.pyqtProperty
-    __version__ = QtCore.PYQT_VERSION_STR
+        # Alias PyQt-specific functions for PySide compatibility.
+        QtCore.Signal = QtCore.pyqtSignal
+        try:
+            QtCore.Slot = QtCore.pyqtSlot
+        except AttributeError:
+            # Not a perfect match but works in simple cases
+            QtCore.Slot = QtCore.pyqtSignature
+
+        QtCore.Property = QtCore.pyqtProperty
+        __version__ = QtCore.PYQT_VERSION_STR
+    except NameError:
+        # QtCore did not get imported, fall back to pyside
+        QT_API = QT_API_PYSIDE
 
-else:  # try importing pyside
+if QT_API == QT_API_PYSIDE:  # try importing pyside
     try:
         from PySide import QtCore, QtGui, __version__, __version_info__
     except ImportError:
