data-driven event system
constellation.zenfyr.dev
1# Commands
2
3In general, you should prefer to implement Brigadier `/` commands, but there are some cases where some additional flexibility is required.
4
5## Creating commands
6
7Creating new commands is easy, you'll have to implement the `Command` interface, create a [MapCodec](https://forge.gemwire.uk/wiki/Codecs) to serialize/deserialize the command and register the codec with `CommandTypes.register()`.
8
9Let's create a simple command which will print a string to standard output.
10
11```java
12public record DummyCommand(String text) implements Command {
13
14 @Override
15 public boolean execute(EventContext context) {
16 System.out.println(text());
17 return true; //Return if execution was successful.
18 }
19
20 @Override
21 public CommandType type() {
22 return null;
23 }
24}
25```
26
27Now create a [Codec](https://forge.gemwire.uk/wiki/Codecs) for your command.
28
29```java
30public static final MapCodec<DummyCommand> CODEC = Codec.STRING.fieldOf("text").xmap(DummyCommand::new, DummyCommand::text);
31```
32
33With that done, we'll have to register the command to get our `CommandType`.
34
35```java
36public static final CommandType DUMMY = CommandType.register(new Identifier("modid", "print"), DummyCommand.CODEC);
37```
38
39Now return this type in `type()`.
40
41```java
42@Override
43public CommandType type() {
44 return MyModInit.DUMMY;
45}
46```
47
48## EventContext
49
50EventContext allows you to retrieve the `LootContext` which is passed with the event type.
51
52```java
53context.lootContext().getWorld(); //Returns a ServerWorld.
54
55context.lootContext().get(LootContextParameters.TOOL); //Returns the prameter or null if not present.
56
57context.lootContext().requireParameter(LootContextParameters.TOOL); //Returns the parameter or throws an exception if not present.
58```