Always resolve a command to a Code object.

Allows downstream clients to rely on numerics before and after a name is defined for that command. Closes #214.

irc/client.py

@@ -340,7 +340,7 @@ def _process_line(self, line):
         grp = _rfc_1459_command_regexp.match(line).group
 
         source = NickMask.from_group(grp("prefix"))
-        command = self._command_from_group(grp("command"))
+        command = events.Code.lookup(grp("command"))
         arguments = message.Arguments.from_group(grp('argument'))
         tags = message.Tag.from_group(grp('tags'))
 
@@ -431,12 +431,6 @@ def _handle_other(self, arguments, command, source, tags):
         event = Event(command, source, target, arguments, tags)
         self._handle_event(event)
 
-    @staticmethod
-    def _command_from_group(group):
-        command = group.lower()
-        # Translate numerics into more readable strings.
-        return events.numeric.get(command, command)
-
     def _handle_event(self, event):
         """[Internal]"""
         self.reactor._handle_event(self, event)

irc/events.py

@@ -19,6 +19,42 @@ def __init__(self, code, name):
     def __int__(self):
         return int(self.code)
 
+    @staticmethod
+    def lookup(command) -> 'Code':
+        """
+        Lookup a command by numeric or by name.
+
+        >>> Code.lookup('002')
+        'yourhost'
+        >>> Code.lookup('002').code
+        '002'
+        >>> int(Code.lookup('002'))
+        2
+        >>> int(Code.lookup('yourhost'))
+        2
+        >>> Code.lookup('yourhost').code
+        '002'
+
+        If a command is supplied that's an unrecognized name or code,
+        a Code object is still returned.
+        >>> fallback = Code.lookup('Unknown-command')
+        >>> fallback
+        'unknown-command'
+        >>> fallback.code
+        'unknown-command'
+        >>> int(fallback)
+        Traceback (most recent call last):
+        ...
+        ValueError: invalid literal for int() with base 10: 'unknown-command'
+        >>> fallback = Code.lookup('999')
+        >>> fallback
+        '999'
+        >>> int(fallback)
+        999
+        """
+        fallback = Code(command.lower(), command.lower())
+        return numeric.get(command, _by_name.get(command.lower(), fallback))
+
 
 _codes = itertools.starmap(
     Code,
@@ -33,6 +69,8 @@ def __int__(self):
 
 codes = {v: k for k, v in numeric.items()}
 
+_by_name = {v: v for v in numeric.values()}
+
 generated = [
     "dcc_connect",
     "dcc_disconnect",