[Tutor] Introduction to the cmd Module

[Sean 'Shaleh' Perry]

On Friday 27 September 2002 10:50, Alan Colburn wrote:
>
> For example, consider this simple script:
> import cmd
> class Test(cmd.Cmd):
>     def __init__(self):
>         cmd.Cmd.__init__(self)
>         self.prompt=3D"% "
>     def do_printHello(self):
>         print 'hello'
> x=3DTest()
> x.cmdloop()
>
> The new prompt appears, but the printHello command generates an error
> (do_printHello takes 1 argument, 2 given).
>
> Anybody feel like a brief tutorial? :-)
>

Here is the __doc__ string for the cmd modules.

<quote>
"""A generic class to build line-oriented command interpreters.

Interpreters constructed with this class obey the following conventions:

1. End of file on input is processed as the command 'EOF'.
2. A command is parsed out of each line by collecting the prefix composed
   of characters in the identchars member.
3. A command `foo' is dispatched to a method 'do_foo()'; the do_ method
   is passed a single argument consisting of the remainder of the line.
4. Typing an empty line repeats the last command.  (Actually, it calls th=
e
   method `emptyline', which may be overridden in a subclass.)
5. There is a predefined `help' method.  Given an argument `topic', it
   calls the command `help_topic'.  With no arguments, it lists all topic=
s
   with defined help_ functions, broken into up to three topics; document=
ed
   commands, miscellaneous help topics, and undocumented commands.
6. The command '?' is a synonym for `help'.  The command '!' is a synonym
   for `shell', if a do_shell method exists.
7. If completion is enabled, completing commands will be done automatical=
ly,
   and completing of commands args is done by calling complete_foo() with
   arguments text, line, begidx, endidx.  text is string we are matching
   against, all returned matches must begin with it.  line is the current
   input line (lstripped), begidx and endidx are the beginning and end
   indexes of the text being matched, which could be used to provide
   different completion depending upon which position the argument is in.

The `default' method may be overridden to intercept commands for which th=
ere
is no do_ method.
               =20
The `completedefault' method may be overridden to intercept completions f=
or
commands that have no complete_ method.

The data member `self.ruler' sets the character used to draw separator li=
nes
in the help messages.  If empty, no ruler line is drawn.  It defaults to =
"=3D".

If the value of `self.intro' is nonempty when the cmdloop method is calle=
d,
it is printed out on interpreter startup.  This value may be overridden
via an optional argument to the cmdloop() method.

The data members `self.doc_header', `self.misc_header', and
`self.undoc_header' set the headers used for the help function's
listings of documented functions, miscellaneous topics, and undocumented
functions respectively.

These interpreters use raw_input; thus, if the readline module is loaded,
they automatically support Emacs-like command history and editing feature=
s.
"""
</quote>

Item number 3. gives you the answer to your problem.  Every do_??? method=
 must=20
take a parameter which is the rest of the input line.  You then read this=
=20
value to get your arguments.