Using Action in Event

[lanhoang712]

Hi, how do you define an action such as to create an action-based event?
I am trying this https://textworld.readthedocs.io/en/stable/textworld.generator.game.html?highlight=event#textworld.generator.game.Event but could not quite figure out how to define an action
For example:
apple = M.new(type='f', name='apple')
eat = Action(name='eat', preconditions=[], postconditions=[M.new_fact("eaten", apple)])
event_1 = Event(actions=[eat], commands='eat the apple')
q1 = Quest(win_events=[event_1]
but this produces an error of AttributeError: 'NoneType' object has no attribute 'items'

[MarcCote]

Hi, correct me if I'm wrong but I believe you want something like this right?

apple = M.new(type='f', name='apple')
apple_eaten_event = Event(conditions={M.new_fact("eaten", apple)})
q1 = Quest(win_events=[apple_eaten_event]

If you really wish to define a quest according to an action, you can do the following:

room = M.new("kitchen")
apple = M.new(type='f', name='apple')
room.add(apple)

q1 = M.new_quest_using_commands(["take apple", "eat apple"])

or

apple_eaten_event = M.new_event_using_commands(["take apple", "eat apple"])
q1 = Quest(win_events=[apple_eaten_event]

Let me know if that's not it. Happy to discuss it more.

[lanhoang712]

Perfect, thank you yes that's what I want to do. When would you use the object Action and can it be used for new action?

[MarcCote]

Great!

Regarding your follow-up question, under the hood, the Event class will look at the last actions and use its postconditions as the conditions. So, your original code is totally fine to create Event and Quest objects.

However, when building the game, TextWorld tries to infer the text commands from the event's actions. In your case, the eat action does not match any rule found in TextWorld's KnowledgeBase.

from textworld.generator import GameMaker, Event, Quest
from textworld.logic import Action

M = GameMaker()
apple = M.new(type='f', name='apple')
eat = Action(name='eat', preconditions=[], postconditions=[M.new_fact("eaten", apple)])
print(eat)
print(M.options.kb.logic.rules['eat'])

eat ::  -> eaten(f_0: f)       # print(eat)
eat :: in(f, I) -> eaten(f)    # print(M.options.kb.logic.rules['eat'])

As you can see, your new action is missing the precondition facts to match the existing eat rule from the KnowledgeBase.

For a completely new action (i.e., that is not already in the KB), you would need to add its Rule (i.e., the general form of an action) first. To do so, you will have to add a new .twl logic file containing the new rule, any new predicates, and the matching Inform7 code. As an example, you can check the tw_cooking games, in particular meal.twl.

Since extending TextWorld is far from being user-friendly at the moment, I'm happy to help you out creating new logic if that's something you need.

[lanhoang712]

Hi Marc, thank you and sorry for the delay in responding. These examples and the twl file are perfect in explaining how to add actions/rules to the game. Thank you so much! Let me have a play with these and ask you further if I struggle with the new logic :).