Question

Is there an easy way to add arguments with values to python3‘s cmd.Cmd?

For example, it’s easy to implement commands with simple parameters:

> action1 param1 param2

by adding do_action1() and complete_action1(), to complete I can search the list of existing parameters.

But how would you implemented parameters with values, for example:

> action1 param1=234 param2=SomeTextValue

or

> action1 param1 234 param2 SomeTextValue

where param1 would be set to 234 and param2 to SomeTextValue.

Can this be parsed by cmd.Cmd?

I can think only about getting the whole argument list in do_action1( self, params = None ) and then parse it myself.

If I use optparse the parameters would have to be prefixed with dash like -p or --param1 and --param2, so to get completion in cmd.Cmd I would have to type 2 dashes first …

> action1 --param1=234 --param2=SomeTextValue

If I have to manually parse the parameters is there any python3 module like optparse which does not expect the parameters to have 2 dash prefix?

Any suggestions?

Answer 1

Well, cmd.Cmd doesn’t actually do a whole lot of parsing for you, anyway. So, yes, you can handle parameters with arguments simply by completing parameters with a trailing =, and parsing the commands yourself:

import cmd

def parse(arg):
    return tuple(k.partition('=') for k in arg.split())

class MyShell(cmd.Cmd):
    def do_foo(self, arg):
        for x, _, y in parse(arg):
            print(x, y)

    def complete_foo(self, text, line, begidx, endidx):
        # Cmd treats = as the end of params; we don't want that.
        if line.endswith('='):
            return ()

        opts = ['param1=', 'param2', 'param3=']
        return [opt for opt in opts if opt.startswith(text)]

MyShell().cmdloop()

Example usage:

(Cmd) foo param<TAB>
param1=  param2   param3=  
(Cmd) foo param1=a param
param1=  param2   param3=  
(Cmd) foo param1=a param2 param3=ah
param1 a
param2 
param3 ah

Note that our completions contain a trailing = as a hint to the user, to let them know a parameter can be passed.