Keep a reference to last execution result on the shell.

In particular to know if the last command has failed.

Note:

Cannot keep a handle on the result object, or it does not get garbage
collected until end of next run, which break some assumption about when
__del__ is called.

IPython/core/interactiveshell.py

@@ -166,6 +166,10 b' class ExecutionResult(object):'
         if self.error_in_exec is not None:
             raise self.error_in_exec
 
+    def __repr__(self):
+        return '<%s object at %x, execution_count=%s error_before_exec=%s error_in_exec=%s result=%s>' %\
+                (self.__class__.__qualname__, id(self), self.execution_count, self.error_before_exec, self.error_in_exec, repr(self.result))
+
 
 class InteractiveShell(SingletonConfigurable):
     """An enhanced, interactive shell for Python."""
@@ -434,6 +438,8 b' class InteractiveShell(SingletonConfigurable):'
     # Tracks any GUI loop loaded for pylab
     pylab_gui_select = None
 
+    last_execution_succeeded = Bool(True, help='Did last executed command succeeded')
+
     def __init__(self, ipython_dir=None, profile_dir=None,
                  user_module=None, user_ns=None,
                  custom_exceptions=((), None), **kwargs):
@@ -2607,6 +2613,7 b' class InteractiveShell(SingletonConfigurable):'
         result = ExecutionResult()
 
         if (not raw_cell) or raw_cell.isspace():
+            self.last_execution_succeeded = True
             return result
         
         if silent:
@@ -2617,6 +2624,7 b' class InteractiveShell(SingletonConfigurable):'
 
         def error_before_exec(value):
             result.error_before_exec = value
+            self.last_execution_succeeded = False
             return result
 
         self.events.trigger('pre_execute')
@@ -2703,8 +2711,10 b' class InteractiveShell(SingletonConfigurable):'
 
                 # Execute the user code
                 interactivity = "none" if silent else self.ast_node_interactivity
-                self.run_ast_nodes(code_ast.body, cell_name,
+                has_raised = self.run_ast_nodes(code_ast.body, cell_name,
                    interactivity=interactivity, compiler=compiler, result=result)
+                
+                self.last_execution_succeeded = not has_raised
 
                 # Reset this so later displayed values do not modify the
                 # ExecutionResult