Event Dependencies#

Custom events can be orchestrated to run based on the occurrence of other events through the use of dependencies.

Overview#

Event dependencies can be implemented by decorating a method within an event definition class with either @dependency or @early_dependency.

@dependency - triggers after any listener contents of the dependency event
@early_dependency - triggers before any listener contents of the dependency event

These decorators operate similarly to the familiar @event decorator, but they function differently internally. They also make use of the self parameter.

Warning

These decorators are purpose-built for use exclusively inside event definitions and should not be employed elsewhere.

Basic Example#

Let’s illustrate the concept of event dependencies with an example player_use_magic_wand event.

You can also find this example on GitHub.

src
└── data
    └── magic_wand
        └── modules
            ├── events.bolt
            └── main.bolt
beet.yml

events.bolt

from crankshaft:api import CustomEvent, dependency

class PlayerUseMagicWand(CustomEvent):
    @dependency
    def player_use_coas(self):
        if data entity @s SelectedItem.tag{custom_item_id: "magic_wand"}:
            self.trigger()

Here we establish a dependency using the @dependency decorator. The chosen dependency event is player_use_coas. When this event is triggered, it will execute the contents of our designated method.

Following this, we conduct a straightforward NBT check to verify that the player is holding the correct item before triggering the event.

main.bolt

import ./events as _
from crankshaft:api import event

@event
def player_use_magic_wand():
    anchored eyes positioned ^ ^ ^6:
        summon sheep ~ ~ ~ {CustomName: '{"text": "jeb_"}'}
        particle firework ~ ~ ~ 0 0 0 0.2 50 force
        particle flash ~ ~ ~ 0 0 0 0 0 force

beet.yml

output: dist

require:
  - bolt
  - crankshaft

data_pack:
  load: 'src'

pipeline:
  - mecha

meta:
  bolt:
    entrypoint: '*:main'