introduce UsageError

IPython/ipapi.py

@@ -86,6 +86,13 b' class TryNext(Exception):'
         self.args = args
         self.kwargs = kwargs
 
+class UsageError(Exception):
+    """ Error in magic function arguments, etc.
+    
+    Something that probably won't warrant a full traceback, but should
+    nevertheless interrupt a macro / batch file.   
+    """
+
 class IPyAutocall:
     """ Instances of this class are always autocalled
     

IPython/iplib.py

@@ -6,7 +6,7 b' Requires Python 2.3 or newer.'
 
 This file contains all the classes and helper functions specific to IPython.
 
-$Id: iplib.py 2725 2007-09-07 08:59:10Z vivainio $
+$Id: iplib.py 2746 2007-09-08 14:00:21Z vivainio $
 """
 
 #*****************************************************************************
@@ -471,7 +471,7 b' class InteractiveShell(object,Magic):'
         except HomeDirError,msg:
             fatal(msg)
 
-        self.dir_stack = [os.getcwd().replace(self.home_dir,'~')]
+        self.dir_stack = []
 
         # Functions to call the underlying shell.
 
@@ -1488,6 +1488,8 b' want to merge them back into the new files.""" % locals()'
 
         if etype is SyntaxError:
             self.showsyntaxerror(filename)
+        elif etype is IPython.ipapi.UsageError:
+            print "UsageError:", value
         else:
             # WARNING: these variables are somewhat deprecated and not
             # necessarily safe to use in a threaded environment, but tools