Allow docs to build without PyQt installed.

PyQt/PySide is needed to list the config options for the Qt console. But
some environments and contributors may not have it, and it's not always
easy to install. This prints a warning and skips the list of Qt console
options if the import fails.

docs/autogen_config.py

@@ -1,74 +1,80 b''
 from IPython.utils.text import indent, wrap_paragraphs
 
 from IPython.terminal.ipapp import TerminalIPythonApp
 from IPython.kernel.zmq.kernelapp import IPKernelApp
 from IPython.html.notebookapp import NotebookApp
-from IPython.qt.console.qtconsoleapp import IPythonQtConsoleApp
 
 def document_config_options(classes):
     lines = []
     for cls in classes:
         classname = cls.__name__
         for k, trait in sorted(cls.class_traits(config=True).items()):
             ttype = trait.__class__.__name__
 
             termline = classname + '.' + trait.name
 
             # Choices or type
             if 'Enum' in ttype:
                 # include Enum choices
                 termline += ' : ' + '|'.join(repr(x) for x in trait.values)
             else:
                 termline += ' : ' + ttype
             lines.append(termline)
 
             # Default value
             try:
                 dv = trait.get_default_value()
                 dvr = repr(dv)
             except Exception:
                 dvr = dv = None # ignore defaults we can't construct
             if (dv is not None) and (dvr is not None):
                 if len(dvr) > 64:
                     dvr = dvr[:61]+'...'
                 # Double up backslashes, so they get to the rendered docs
                 dvr = dvr.replace('\\n', '\\\\n')
                 lines.append('    Default: ' + dvr)
                 lines.append('')
 
             help = trait.get_metadata('help')
             if help is not None:
                 help = '\n\n'.join(wrap_paragraphs(help, 76))
                 lines.append(indent(help, 4))
             else:
                 lines.append('    No description')
 
             lines.append('')
     return '\n'.join(lines)
 
 kernel_classes = IPKernelApp().classes
 
 def write_doc(filename, title, classes, preamble=None):
     configdoc = document_config_options(classes)
     with open('source/config/options/%s.rst' % filename, 'w') as f:
         f.write(title + '\n')
         f.write(('=' * len(title)) + '\n')
         f.write('\n')
         if preamble is not None:
             f.write(preamble + '\n\n')
         f.write(configdoc)
 
 if __name__ == '__main__':
     write_doc('terminal', 'Terminal IPython options', TerminalIPythonApp().classes)
     write_doc('kernel', 'IPython kernel options', kernel_classes,
               preamble="These options can be used in :file:`ipython_notebook_config.py` "
               "or in :file:`ipython_qtconsole_config.py`")
     nbclasses = set(NotebookApp().classes) - set(kernel_classes)
     write_doc('notebook', 'IPython notebook options', nbclasses,
               preamble="Any of the :doc:`kernel` can also be used.")
-    qtclasses = set(IPythonQtConsoleApp().classes) - set(kernel_classes)
-    write_doc('qtconsole', 'IPython Qt console options', qtclasses,
-              preamble="Any of the :doc:`kernel` can also be used.")
+
+    try:
+        from IPython.qt.console.qtconsoleapp import IPythonQtConsoleApp
+    except ImportError:
+        print("WARNING: Could not import qtconsoleapp. Config options for the "
+              "Qt Console will not be documented.")
+    else:
+        qtclasses = set(IPythonQtConsoleApp().classes) - set(kernel_classes)
+        write_doc('qtconsole', 'IPython Qt console options', qtclasses,
+                  preamble="Any of the :doc:`kernel` can also be used.")
 
     with open('source/config/options/generated', 'w'):
         pass
  No newline at end of file