如何使用python的cmd获取首字母命令？

Question

I would like to type "c" in my commandline, hit enter and have it run the "command" command. This code does what I want, but it does not use cmd. I would like to use cmd:

import sys

def command():
    print("This is a command")

def quit():
    print("goodbye")
    sys.exit()

def take(item=None):
    if item:
        print("You take %s" % item)
    else:
        print("What would you like to take?")

commands = {
'command': command,
'quit': quit,
'take': take,
}

def complete(text, state):
    print("Here is the text: %s and here is the state %s" % (text, state))

def my_loop():
    while True:
        c = raw_input("\n>")
        if c.strip():
            c = c.split(' ', 1)
            for command in commands:
                if command.startswith(c[0]):c[0] = command
            func = commands.get(c[0], None)
            if func:
                if len(c) == 1:func()
                else:func(c[1])
            else:print("I don't understand that command")

my_loop()

Here is the same using cmd, but it does not run the "command" command when I type "c" and hit enter.

import sys, cmd

class Mcmd(cmd.Cmd):
    prompt = '\n>'

    def default(self, arg):
        print("I do not understand that command. Type 'help' for a list of commands")

    def do_command(self, line):
        print("This is a command")

    def do_quit(self, arg):
        print("See you")
        return True

Mcmd().cmdloop()

How can I get the start of the command to trigger the "command" or "quit" command using cmd? ("c", "co", "com", "comm"...) all trigger the "command" function. I was considering using the new textwrap module, but textwrap has problems being cross-platform. Is there any other way to do this? thank you,

Answer 1

You already managed to figure out how to override the default method, so you can extend that to look up a compatible method from within your Mcmd class. Try something like this:

    def default(self, line):
        command, arg, line = self.parseline(line)
        func = [getattr(self, n) for n in self.get_names()
            if n.startswith('do_' + command)]
        if len(func) == 1:
            return func[0](arg)
        print("I do not understand that command. Type 'help' for a list of commands")

Running that

>a
I do not understand that command. Type 'help' for a list of commands

>c
This is a command

>ca
I do not understand that command. Type 'help' for a list of commands

>co
This is a command

>q
See you

While technically a duplicate of Aliases for commands with Python cmd module the answer isn't quite complete; it doesn't properly address ambiguous cases (say you got both do_command and do_copy , what should happen on the input of c and co ?). Here it only returns if there is a singular match.

Alternatively Python cmd module command aliases is a possible answer, but it's just tedious.