Merge pull request #2874 from rlmv/emptycell

Empty cell warnings

IPython/core/interactiveshell.py

@@ -2119,10 +2119,13 b' class InteractiveShell(SingletonConfigurable):'
         fn = self.find_cell_magic(magic_name)
         if fn is None:
             lm = self.find_line_magic(magic_name)
-            etpl = "Cell magic function `%%%%%s` not found%s."
-            extra = '' if lm is None else (' (But line magic `%%%s` exists, '
-                                    'did you mean that instead?)' % magic_name )
-            error(etpl % (magic_name, extra))
+            etpl = "Cell magic function `%%{0}` not found{1}."
+            extra = '' if lm is None else (' (But line magic `%{0}` exists, '
+                            'did you mean that instead?)'.format(magic_name))
+            error(etpl.format(magic_name, extra))
+        elif cell == '':
+            raise UsageError('%%{0} (with double %) expects code beneath it. '
+                            'Did you mean %{0} (single %)?'.format(magic_name))
         else:
             # Note: this is the distance in the stack to the user's frame.
             # This will need to be updated if the internal calling logic gets

IPython/core/magics/execution.py

@@ -776,6 +776,7 b' python-profiler package from non-free.""")'
                                         posix=False, strict=False)
         if stmt == "" and cell is None:
             return
+        
         timefunc = timeit.default_timer
         number = int(getattr(opts, "n", 0))
         repeat = int(getattr(opts, "r", timeit.default_repeat))

IPython/core/magics/osm.py

@@ -36,6 +36,7 b' from IPython.utils.openpy import source_to_unicode'
 from IPython.utils.path import unquote_filename
 from IPython.utils.process import abbrev_cwd
 from IPython.utils.terminal import set_term_title
+
 #-----------------------------------------------------------------------------
 # Magic implementation classes
 #-----------------------------------------------------------------------------