cmd¶
A generic class to build line-oriented command interpreters.
Interpreters constructed with this class obey the following conventions:
- End of file on input is processed as the command ‘EOF’.
- A command is parsed out of each line by collecting the prefix composed of characters in the identchars member.
- 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.
- Typing an empty line repeats the last command. (Actually, it calls the method `emptyline’, which may be overridden in a subclass.)
- There is a predefined `help’ method. Given an argument `topic’, it calls the command `help_topic’. With no arguments, it lists all topics with defined help_ functions, broken into up to three topics; documented commands, miscellaneous help topics, and undocumented commands.
- The command ‘?’ is a synonym for `help’. The command ‘!’ is a synonym for `shell’, if a do_shell method exists.
- If completion is enabled, completing commands will be done automatically, 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 there is no do_ method.
The `completedefault’ method may be overridden to intercept completions for commands that have no complete_ method.
The data member `self.ruler’ sets the character used to draw separator lines in the help messages. If empty, no ruler line is drawn. It defaults to “=”.
If the value of `self.intro’ is nonempty when the cmdloop method is called, 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 features.