ENH: Add a 'Minimal' xmode option.

This shows only the exception with no Traceback. If the Traceback is
needed, it can be retrieved using %tb.

IPython/core/interactiveshell.py

@@ -580,7 +580,7 class InteractiveShell(SingletonConfigurable):
     separate_out = SeparateUnicode('').tag(config=True)
     separate_out2 = SeparateUnicode('').tag(config=True)
     wildcards_case_sensitive = Bool(True).tag(config=True)
-    xmode = CaselessStrEnum(('Context','Plain', 'Verbose'),
+    xmode = CaselessStrEnum(('Context', 'Plain', 'Verbose', 'Minimal'),
                             default_value='Context',
                             help="Switch modes for the IPython exception handlers."
                             ).tag(config=True)
@@ -1788,7 +1788,7 class InteractiveShell(SingletonConfigurable):
 
         # The interactive one is initialized with an offset, meaning we always
         # want to remove the topmost item in the traceback, which is our own
-        # internal code. Valid modes: ['Plain','Context','Verbose']
+        # internal code. Valid modes: ['Plain','Context','Verbose','Minimal']
         self.InteractiveTB = ultratb.AutoFormattedTB(mode = 'Plain',
                                                      color_scheme='NoColor',
                                                      tb_offset = 1,

IPython/core/magics/basic.py

@@ -363,7 +363,7 Currently the magic system has the following functions:""",
     def xmode(self, parameter_s=''):
         """Switch modes for the exception handlers.
 
-        Valid modes: Plain, Context and Verbose.
+        Valid modes: Plain, Context, Verbose, and Minimal.
 
         If called without arguments, acts as a toggle."""
 

IPython/core/tests/test_ultratb.py

@@ -111,6 +111,9 class NonAsciiTest(unittest.TestCase):
         with tt.AssertPrints(expected):
             ip.run_cell(cell)
 
+        ip.run_cell("%xmode minimal")
+        with tt.AssertPrints(u"Exception: é"):
+            ip.run_cell(cell)
 
 class NestedGenExprTestCase(unittest.TestCase):
     """

IPython/core/ultratb.py

@@ -1251,7 +1251,7 class FormattedTB(VerboseTB, ListTB):
                  parent=None, config=None):
 
         # NEVER change the order of this list. Put new modes at the end:
-        self.valid_modes = ['Plain', 'Context', 'Verbose']
+        self.valid_modes = ['Plain', 'Context', 'Verbose', 'Minimal']
         self.verbose_modes = self.valid_modes[1:3]
 
         VerboseTB.__init__(self, color_scheme=color_scheme, call_pdb=call_pdb,
@@ -1262,7 +1262,8 class FormattedTB(VerboseTB, ListTB):
 
         # Different types of tracebacks are joined with different separators to
         # form a single string.  They are taken from this dict
-        self._join_chars = dict(Plain='', Context='\n', Verbose='\n')
+        self._join_chars = dict(Plain='', Context='\n', Verbose='\n',
+                                Minimal='')
         # set_mode also sets the tb_join_char attribute
         self.set_mode(mode)
 
@@ -1280,6 +1281,8 class FormattedTB(VerboseTB, ListTB):
             return VerboseTB.structured_traceback(
                 self, etype, value, tb, tb_offset, number_of_lines_of_context
             )
+        elif mode == 'Minimal':
+            return ListTB.get_exception_only(self, etype, value)
         else:
             # We must check the source cache because otherwise we can print
             # out-of-date source code.
@@ -1324,6 +1327,9 class FormattedTB(VerboseTB, ListTB):
     def verbose(self):
         self.set_mode(self.valid_modes[2])
 
+    def minimal(self):
+        self.set_mode(self.valid_modes[3])
+
 
 #----------------------------------------------------------------------------
 class AutoFormattedTB(FormattedTB):