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(python2.1-lib.info)Cmd Objects

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Cmd Objects
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A `Cmd' instance has the following methods:

`cmdloop([intro])'
     Repeatedly issue a prompt, accept input, parse an initial prefix
     off the received input, and dispatch to action methods, passing
     them the remainder of the line as argument.

     The optional argument is a banner or intro string to be issued
     before the first prompt (this overrides the `intro' class member).

     If the `readline' module is loaded, input will automatically
     inherit `bash'-like history-list editing (e.g. <Ctrl-P> scrolls
     back to the last command, <Ctrl-N> forward to the next one,
     <Ctrl-F> moves the cursor to the right non-destructively, <Ctrl-B>
     moves the cursor to the left non-destructively, etc.).

     An end-of-file on input is passed back as the string `'EOF''.

     An interpreter instance will recognize a command name `foo' if and
     only if it has a method `do_foo()'.  As a special case, a line
     beginning with the character `?' is dispatched to the method
     `do_help()'.  As another special case, a line beginning with the
     character `!' is dispatched to the method `do_shell' (if such a
     method is defined).

     All subclasses of `Cmd' inherit a predefined `do_help'.  This
     method, called with an argument `bar', invokes the corresponding
     method `help_bar()'.  With no argument, `do_help()' lists all
     available help topics (that is, all commands with corresponding
     `help_*()' methods), and also lists any undocumented commands.

`onecmd(str)'
     Interpret the argument as though it had been typed in response to
     the prompt.  This may be overridden, but should not normally need
     to be; see the `precmd()' and `postcmd()' methods for useful
     execution hooks.  The return value is a flag indicating whether
     interpretation of commands by the interpreter should stop.

`emptyline()'
     Method called when an empty line is entered in response to the
     prompt.  If this method is not overridden, it repeats the last
     nonempty command entered.

`default(line)'
     Method called on an input line when the command prefix is not
     recognized. If this method is not overridden, it prints an error
     message and returns.

`precmd()'
     Hook method executed just before the command line LINE is
     interpreted, but after the input prompt is generated and issued.
     This method is a stub in `Cmd'; it exists to be overridden by
     subclasses.  The return value is used as the command which will be
     executed by the `onecmd()' method; the `precmd()' implementation
     may re-write the command or simply return LINE unchanged.

`postcmd(stop, line)'
     Hook method executed just after a command dispatch is finished.
     This method is a stub in `Cmd'; it exists to be overridden by
     subclasses.  LINE is the command line which was executed, and STOP
     is a flag which indicates whether execution will be terminated
     after the call to `postcmd()'; this will be the return value of
     the `onecmd()' method.  The return value of this method will be
     used as the new value for the internal flag which corresponds to
     STOP; returning false will cause interpretation to continue.

`preloop()'
     Hook method executed once when `cmdloop()' is called.  This method
     is a stub in `Cmd'; it exists to be overridden by subclasses.

`postloop()'
     Hook method executed once when `cmdloop()' is about to return.
     This method is a stub in `Cmd'; it exists to be overridden by
     subclasses.

Instances of `Cmd' subclasses have some public instance variables:

`prompt'
     The prompt issued to solicit input.

`identchars'
     The string of characters accepted for the command prefix.

`lastcmd'
     The last nonempty command prefix seen.

`intro'
     A string to issue as an intro or banner.  May be overridden by
     giving the `cmdloop()' method an argument.

`doc_header'
     The header to issue if the help output has a section for documented
     commands.

`misc_header'
     The header to issue if the help output has a section for
     miscellaneous help topics (that is, there are `help_*()' methods
     without corresponding `do_*()' methods).

`undoc_header'
     The header to issue if the help output has a section for
     undocumented commands (that is, there are `do_*()' methods without
     corresponding `help_*()' methods).

`ruler'
     The character used to draw separator lines under the help-message
     headers.  If empty, no ruler line is drawn.  It defaults to `='.

`use_rawinput'
     A flag, defaulting to true.  If true, `cmdloop()' uses
     `raw_input()' to display a prompt and read the next command; if
     false, `sys.stdout.write()' and `sys.stdin.readline()' are used.