Pattern-based commands and specific actions for empty commands

[blairfrandeen]

I'm writing an application that I use to track my working hours on various projects, and I'm trying to decide if using cmd2 makes sense for my specific use case. In exploring the documentation and examples, I've found two features of my current application that cmd2 doesn't seem to support: Pattern-based commands, and calling a specific function for an empty command.

The principle behind my time tracking application is minimum amount of keystrokes to enter data. Thus if I want to log an activity, any command that starts with a float logs that many hours. Optional arguments can follow that and are parsed accordingly. For example, a command such as 1.25 2 t example command is parsed as "1.25 hours on work mode 2 (deep work) on project code t (time tracker app) with comment example command."

Having optional arguments in cmd2 is easy enough, but can I run these without any command to begin with? Having to type add_entry prior to any arguments is not an improvement, and cmd2 doesn't accept def do_(): as a function declaration or "" as an alias.

Another feature of this application is that it reads my Outlook calendar, and prompts me to make time entries based on that. For example, if I have a 1 hour team meeting on my outlook calendar, the application will prompt me as to whether that was correct. If it was, I simply press <enter> and the details from the Outlook event are entered in my time log. If it wasn't, I can use arguments as described above to modify the entry before its recorded.

Is there a way to use an empty command to do something specific, based on the state of the program?

I've implemented all of the above with my own console module in my project called titr. It works, but the console is rough around the edges, and doesn't have some of the nicer features of cmd2 such as command history. The console is fundamentally different than cmd2 in that it uses function decorators to collect console commands, so switching to cmd2 would mean a major refactoring effort.

Looking forward to hearing any thoughts and feedback.

[anselor]

This behavior is very different from how most of cmd behaves. There are 2 avenues you could explore, though.

In the Cmd class, all commands eventually hit the onecmd() function where it attempts to locate the do_ function that corresponds to a command. If it can't find a command, it calls the default() function. You could try overriding default() and, failing that, try overriding onecmd(). If you have custom state tracking, you can probably use as the basis for determining which of your functions you want to call.

Completion starts by calling the Cmd.complete() function which then looks up the command function and determines the type of completion depending on the specifics of the command function.

As for the note about decorators vs do_ functions - that's a holdover from cmd2 being built on top of python's Cmd which depends on these do_ functions. It may be possible for us to support a decorator based command registration in the future.

[blairfrandeen]

Thanks, this pointed me in the right direction. I was able to get the pattern-based behavior by modifying onecmd, and the empty-command behavior by modifying _complete_statement. The latter is a bit hacky in that I have to call self.statement_parser.parse() with my preferred function as the argument, but it seems to work.