# Player Characters

In the previous lesson about rules and dice rolling we made some assumptions about the “Player Character” entity:

- It should store Abilities on itself as `character.strength`, `character.constitution` etc.

- It should have a `.heal(amount)` method.

So we have some guidelines of how it should look! A Character is a database entity with values that should be able to be changed over time. It makes sense to base it off Evennia’s DefaultCharacter Typeclass. The Character class is like a ‘character sheet’ in a tabletop RPG, it will hold everything relevant to that PC.

## Inheritance structure

Player Characters (PCs) are not the only “living” things in our world. We also have NPCs (like shopkeepers and other friendlies) as well as monsters (mobs) that can attack us.

In code, there are a few ways we could structure this. If NPCs/monsters were just special cases of PCs, we could use a class inheritance like this:

    from evennia import DefaultCharacter

    class EvAdventureCharacter(DefaultCharacter):
        # stuff

    class EvAdventureNPC(EvAdventureCharacter):
        # more stuff

    class EvAdventureMob(EvAdventureNPC):
        # more stuff

All code we put on the `Character` class would now be inherited to `NPC` and `Mob` automatically.

However, in Knave, NPCs and particularly monsters are not using the same rules as PCs - they are simplified to use a Hit-Die (HD) concept. So while still character-like, NPCs should be separate from PCs like this:

    from evennia import DefaultCharacter

    class EvAdventureCharacter(DefaultCharacter):
        # stuff

    class EvAdventureNPC(DefaultCharacter):
        # separate stuff

    class EvAdventureMob(EvadventureNPC):
        # more separate stuff

Nevertheless, there are some things that should be common for all ‘living things’:

- All can take damage.

- All can die.

- All can heal

- All can hold and lose coins

- All can loot their fallen foes.

- All can get looted when defeated.

We don’t want to code this separately for every class but we no longer have a common parent class to put it on. So instead we’ll use the concept of a mixin class:

    from evennia import DefaultCharacter

    class LivingMixin:
        # stuff common for all living things

    class EvAdventureCharacter(LivingMixin, DefaultCharacter):
        # stuff

    class EvAdventureNPC(LivingMixin, DefaultCharacter):
        # stuff

    class EvAdventureMob(LivingMixin, EvadventureNPC):
        # more stuff

Above, the `LivingMixin` class cannot work on its own - it just ‘patches’ the other classes with some extra functionality all living things should be able to do. This is an example of multiple inheritance. It’s useful to know about, but one should not over-do multiple inheritance since it can also get confusing to follow the code.

## Living mixin class

> Create a new module `mygame/evadventure/characters.py`

Let’s get some useful common methods all living things should have in our game.

    # in mygame/evadventure/characters.py

    from .rules import dice

    class LivingMixin:

        # makes it easy for mobs to know to attack PCs
        is_pc = False

        def heal(self, hp):
            """
            Heal hp amount of health, not allowing to exceed our max hp

            """
            damage = self.hp_max - self.hp
            healed = min(damage, hp)
            self.hp += healed

            self.msg("You heal for {healed} HP.")

        def at_pay(self, amount):
            """When paying coins, make sure to never detract more than we have"""
            amount = min(amount, self.coins)
            self.coins -= amount
            return amount

        def at_damage(self, damage, attacker=None):
            """Called when attacked and taking damage."""
            self.hp -= damage

        def at_defeat(self):
            """Called when defeated. By default this means death."""
            self.at_death()

        def at_death(self):
            """Called when this thing dies."""
            # this will mean different things for different living things
            pass

        def at_do_loot(self, looted):
            """Called when looting another entity"""
            looted.at_looted(self)

        def at_looted(self, looter):
            """Called when looted by another entity"""

            # default to stealing some coins
            max_steal = dice.roll("1d10")
            stolen = self.at_pay(max_steal)
            looter.coins += stolen

Most of these are empty since they will behave differently for characters and npcs. But having them in the mixin means we can expect these methods to be available for all living things.

## Character class

We will now start making the basic Character class, based on what we need from Knave.

    # in mygame/evadventure/characters.py

    from evennia import DefaultCharacter, AttributeProperty
    from .rules import dice

    class LivingMixin:
        # ...

    class EvAdventureCharacter(LivingMixin, DefaultCharacter):
        """
        A character to use for EvAdventure.
        """
        is_pc = True

        strength = AttributeProperty(1)
        dexterity = AttributeProperty(1)
        constitution = AttributeProperty(1)
        intelligence = AttributeProperty(1)
        wisdom = AttributeProperty(1)
        charisma = AttributeProperty(1)

        hp = AttributeProperty(8)
        hp_max = AttributeProperty(8)

        level = AttributeProperty(1)
        xp = AttributeProperty(0)
        coins = AttributeProperty(0)

        def at_defeat(self):
            """Characters roll on the death table"""
            if self.location.allow_death:
                # this allow rooms to have non-lethal battles
                dice.roll_death(self)
            else:
                self.location.msg_contents(
                    "$You() $conj(collapse) in a heap, alive but beaten.",
                    from_obj=self)
                self.heal(self.hp_max)

        def at_death(self):
            """We rolled 'dead' on the death table."""
            self.location.msg_contents(
                "$You() collapse in a heap, embraced by death.",
                from_obj=self)
            # TODO - go back into chargen to make a new character!

We make an assumption about our rooms here - that they have a property `.allow_death`. We need to make a note to actually add such a property to rooms later!

In our `Character` class we implement all attributes we want to simulate from the Knave ruleset. The `AttributeProperty` is one way to add an Attribute in a field-like way; these will be accessible on every character in several ways:

- As `character.strength`

- As `character.db.strength`

- As `character.attributes.get("strength")`

See Attributes for seeing how Attributes work.

Unlike in base Knave, we store `coins` as a separate Attribute rather than as items in the inventory, this makes it easier to handle barter and trading later.

We implement the Player Character versions of `at_defeat` and `at_death`. We also make use of `.heal()` from the `LivingMixin` class.

### Funcparser inlines

This piece of code is worth some more explanation:

    self.location.msg_contents(
        "$You() $conj(collapse) in a heap, alive but beaten.",
        from_obj=self)

Remember that `self` is the Character instance here. So `self.location.msg_contents` means “send a message to everything inside my current location”. In other words, send a message to everyone in the same place as the character.

The `$You() $conj(collapse)` are FuncParser inlines. These are functions that execute in the string. The resulting string may look different for different audiences. The `$You()` inline function will use `from_obj` to figure out who ‘you’ are and either show your name or ‘You’. The `$conj()` (verb conjugator) will tweak the (English) verb to match.

- You will see: `"You collapse in a heap, alive but beaten."`

- Others in the room will see: `"Thomas collapses in a heap, alive but beaten."`

Note how `$conj()` chose `collapse/collapses` to make the sentences grammatically correct.

### Backtracking

We make our first use of the `rules.dice` roller to roll on the death table! As you may recall, in the previous lesson, we didn’t know just what to do when rolling ‘dead’ on this table. Now we know - we should be calling `at_death` on the character. So let’s add that where we had TODOs before:

    # mygame/evadventure/rules.py

    class EvAdventureRollEngine:

        # ...

        def roll_death(self, character):
            ability_name = self.roll_random_table("1d8", death_table)

            if ability_name == "dead":
                # kill the character!
                character.at_death()  # <------ TODO no more
            else:
                # ...

                if current_ability < -10:
                    # kill the character!
                    character.at_death()  # <------- TODO no more
                else:
                    # ...

## Connecting the Character with Evennia

You can easily make yourself an `EvAdventureCharacter` in-game by using the `type` command:

    type self = evadventure.characters.EvAdventureCharacter

You can now do `examine self` to check your type updated.

If you want all new Characters to be of this type you need to tell Evennia about it. Evennia uses a global setting `BASE_CHARACTER_TYPECLASS` to know which typeclass to use when creating Characters (when logging in, for example). This defaults to `typeclasses.characters.Character` (that is, the `Character` class in `mygame/typeclasses/characters.py`).

There are thus two ways to weave your new Character class into Evennia:

1. Change `mygame/server/conf/settings.py` and add `BASE_CHARACTER_CLASS = "evadventure.characters.EvAdventureCharacter"`.

2. Or, change `typeclasses.characters.Character` to inherit from `EvAdventureCharacter`.

You must always reload the server for changes like this to take effect.

Important

In this tutorial we are making all changes in a folder `mygame/evadventure/`. This means we can isolate our code but means we need to do some extra steps to tie the character (and other objects) into Evennia. For your own game it would be just fine to start editing `mygame/typeclasses/characters.py` directly instead.

## Unit Testing

> Create a new module `mygame/evadventure/tests/test_characters.py`

For testing, we just need to create a new EvAdventure character and check that calling the methods on it doesn’t error out.

    # mygame/evadventure/tests/test_characters.py

    from evennia.utils import create
    from evennia.utils.test_resources import BaseEvenniaTest

    from ..characters import EvAdventureCharacter

    class TestCharacters(BaseEvenniaTest):
        def setUp(self):
            super().setUp()
            self.character = create.create_object(EvAdventureCharacter, key="testchar")

        def test_heal(self):
            self.character.hp = 0
            self.character.hp_max = 8

            self.character.heal(1)
            self.assertEqual(self.character.hp, 1)
            # make sure we can't heal more than max
            self.character.heal(100)
            self.assertEqual(self.character.hp, 8)

        def test_at_pay(self):
            self.character.coins = 100

            result = self.character.at_pay(60)
            self.assertEqual(result, 60)
            self.assertEqual(self.character.coins, 40)

            # can't get more coins than we have
            result = self.character.at_pay(100)
            self.assertEqual(result, 40)
            self.assertEqual(self.character.coins, 0)

        # tests for other methods ...

If you followed the previous lessons, these tests should look familiar. Consider adding tests for other methods as practice. Refer to previous lessons for details.

For running the tests you do:

     evennia test --settings settings.py .evadventure.tests.test_character

## About races and classes

Knave doesn’t have any D&D-style classes (like Thief, Fighter etc). It also does not bother with races (like dwarves, elves etc). This makes the tutorial shorter, but you may ask yourself how you’d add these functions.

In the framework we have sketched out for Knave, it would be simple - you’d add your race/class as an Attribute on your Character:

    # mygame/evadventure/characters.py

    from evennia import DefaultCharacter, AttributeProperty
    # ...

    class EvAdventureCharacter(LivingMixin, DefaultCharacter):

        # ...

        charclass = AttributeProperty("Fighter")
        charrace = AttributeProperty("Human")

We use `charclass` rather than `class` here, because `class` is a reserved Python keyword. Naming `race` as `charrace` thus matches in style.

We’d then need to expand our rules module (and later character generation to check and include what these classes mean.

## Summary

With the `EvAdventureCharacter` class in place, we have a better understanding of how our PCs will look like under Knave.

For now, we only have bits and pieces and haven’t been testing this code in-game. But if you want you can swap yourself into `EvAdventureCharacter` right now. Log into your game and run the command

    type self = evadventure.characters.EvAdventureCharacter

If all went well, `ex self` will now show your typeclass as being `EvAdventureCharacter`. Check out your strength with

    py self.strength = 3

Important

When doing `ex self` you will not see all your Abilities listed yet. That’s because Attributes added with `AttributeProperty` are not available until they have been accessed at least once. So once you set (or look at) `.strength` above, `strength` will show in `examine` from then on.