# Command Prompt

A prompt is quite common in MUDs. The prompt display useful details about your character that you are likely to want to keep tabs on at all times, such as health, magical power etc. It might also show things like in-game time, weather and so on. Many modern MUD clients (including Evennia’s own webclient) allows for identifying the prompt and have it appear in a correct location (usually just above the input line). Usually it will remain like that until it is explicitly updated.

## Sending a prompt

A prompt is sent using the `prompt` keyword to the `msg()` method on objects. The prompt will be sent without any line breaks.

        self.msg(prompt="HP: 5, MP: 2, SP: 8")

You can combine the sending of normal text with the sending (updating of the prompt):

        self.msg("This is a text", prompt="This is a prompt")

You can update the prompt on demand, this is normally done using OOB-tracking of the relevant Attributes (like the character’s health). You could also make sure that attacking commands update the prompt when they cause a change in health, for example.

Here is a simple example of the prompt sent/updated from a command class:

        from evennia import Command

        class CmdDiagnose(Command):
            """
            see how hurt your are

            Usage:
              diagnose [target]

            This will give an estimate of the target's health. Also
            the target's prompt will be updated.
            """
            key = "diagnose"

            def func(self):
                if not self.args:
                    target = self.caller
                else:
                    target = self.search(self.args)
                    if not target:
                        return
                # try to get health, mana and stamina
                hp = target.db.hp
                mp = target.db.mp
                sp = target.db.sp

                if None in (hp, mp, sp):
                    # Attributes not defined
                    self.caller.msg("Not a valid target!")
                    return

                text = f"You diagnose {target} as having {hp} health, {mp} mana and {sp} stamina."
                prompt = f"{hp} HP, {mp} MP, {sp} SP"
                self.caller.msg(text, prompt=prompt)

## A prompt sent with every command

The prompt sent as described above uses a standard telnet instruction (the Evennia web client gets a special flag). Most MUD telnet clients will understand and allow users to catch this and keep the prompt in place until it updates. So in principle you’d not need to update the prompt every command.

However, with a varying user base it can be unclear which clients are used and which skill level the users have. So sending a prompt with every command is a safe catch-all. You don’t need to manually go in and edit every command you have though. Instead you edit the base command class for your custom commands (like `MuxCommand` in your `mygame/commands/command.py` folder) and overload the `at_post_cmd()` hook. This hook is always called after the main `func()` method of the Command.

    from evennia import default_cmds

    class MuxCommand(default_cmds.MuxCommand):
        # ...
        def at_post_cmd(self):
            "called after self.func()."
            caller = self.caller
            prompt = f"{caller.db.hp} HP, {caller.db.mp} MP, {caller.db.sp} SP"
            caller.msg(prompt=prompt)

### Modifying default commands

If you want to add something small like this to Evennia’s default commands without modifying them directly the easiest way is to just wrap those with a multiple inheritance to your own base class:

    # in (for example) mygame/commands/mycommands.py

    from evennia import default_cmds
    # our custom MuxCommand with at_post_cmd hook
    from commands.command import MuxCommand

    # overloading the look command
    class CmdLook(default_cmds.CmdLook, MuxCommand):
        pass

The result of this is that the hooks from your custom `MuxCommand` will be mixed into the default `CmdLook` through multiple inheritance. Next you just add this to your default command set:

    # in mygame/commands/default_cmdsets.py

    from evennia import default_cmds
    from commands import mycommands

    class CharacterCmdSet(default_cmds.CharacterCmdSet):
        # ...
        def at_cmdset_creation(self):
            # ...
            self.add(mycommands.CmdLook())

This will automatically replace the default `look` command in your game with your own version.