Allow irc.error() to be called with no arguments and act as if ArgumentError was raised.

src/callbacks.py

@@ -432,6 +432,7 @@ class IrcObjectProxy(RichReplyMethods):
         self.args = copy.deepcopy(args)
         self.counter = 0
         self.finished = False # Used in _callInvalidCommands.
+        self.commandMethod = None # Used in error.
         self._resetReplyAttributes()
         if not args:
             self.finalEvaled = True
@@ -472,6 +473,8 @@ class IrcObjectProxy(RichReplyMethods):
                 cb.invalidCommand(self, self.msg, self.args)
 
     def _callCommand(self, name, command, cb):
+        try:
+            self.commandMethod = command
             try:
                 cb.callCommand(command, self, self.msg, self.args)
             except (getopt.GetoptError, ArgumentError):
@@ -488,6 +491,8 @@ class IrcObjectProxy(RichReplyMethods):
                     self.error(utils.exnToString(e))
                 else:
                     self.replyError()
+        finally:
+            self.commandMethod = None
             
     def finalEval(self):
         assert not self.finalEvaled, 'finalEval called twice.'
@@ -642,12 +647,19 @@ class IrcObjectProxy(RichReplyMethods):
             self.args[self.counter] = s
             self.evalArgs()
 
-    def error(self, s, private=None, notice=None, **kwargs):
+    def error(self, s='', private=None, notice=None, **kwargs):
+        if s:
             if not isinstance(self.irc, irclib.Irc):
                 self.irc.error(s, private)
             else:
                 self.irc.queueMsg(error(self.msg, s, private=private,
                                         notice=notice, **kwargs))
+        else:
+            # No argument, let's raise ArgumentError.
+            if self.commandMethod is not None:
+                # We can recurse here because it only gets called once.
+                self.error(formatArgumentError(self.commandMethod),
+                           private=private, notice=notice, **kwargs)
         self.finished = True
 
     def getRealIrc(self):

test/test_callbacks.py

@@ -266,6 +266,9 @@ class PrivmsgTestCase(ChannelPluginTestCase):
         finally:
             conf.supybot.reply.errorInPrivate.setValue(original)
 
+    def testErrorNoArgumentIsArgumentError(self):
+        self.assertHelp('eval irc.error()')
+
     def testErrorWithNotice(self):
         try:
             original = conf.supybot.reply.errorWithNotice()