[ Python 常見問題 ] Aliases for commands with Python cmd module

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Question
How can I create an alias for a command in a line-oriented command interpreter implemented using the cmd module?

To create a command, I must implement the do_cmd method. But I have commands with long names (like constraint) and I want to provide aliases (in fact, shortcuts) for these commands (like co). How can I do that? One possibility that came to my mind is to implement the do_alias (like do_co) method and just calling do_cmd (do_constraint) in this method. But this brings me new commands in the help of the CLI.

Is there any other way to achieve this? Or may be is there a way to hide commands from the help output?

HowTo
You can overwrite the default method and search for a suitable command handler (as already suggested by Brian):

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1. import cmd  
2. import sys  
3.   
4. class WithAliasCmd(cmd.Cmd):  
5.     def do_long_cmd_name(self, arg):  
6.         print("Hello world!")  
7.   
8.     def default(self, line):  
9.         cmd, arg, line = self.parseline(line)  
10.         func = [getattr(self, n) for n in self.get_names() if n.startswith('do_' + cmd)]  
11.         if func: # maybe check if exactly one or more elements, and tell the user  
12.             func[0](arg)  
13.         elif cmd == "hello": # "hello" is an alias for command long_cmd_name  
14.             return self.do_long_cmd_name(arg)  
15.   
16.     def do_bye(self, arg):  
17.         print("Bye")  
18.         return True  
19.   
20.   
21. if __name__ == '__main__':  
22.     WithAliasCmd().cmdloop()  

Execution output:

C:\tmp> python cmd_alias.py
(Cmd) ?

Documented commands (type help <topic>):
========================================
help

Undocumented commands:
======================
bye long_cmd_name

(Cmd) long_cmd_name
Hello world!
(Cmd) hello
Hello world!