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Most of the time working with PraxisCORE you do not need to manage references to objects manually. However, Ref<T> offers a way to hook into the reference handling lifecycle inside the runtime when this is required eg. for interacting with other libraries. It provides a safe way for carrying references across code changes, and determining what happens when code is updated or the reference deleted.

The reference must be initialized before use, often with a constructor references. Handlers can be added for onReset() and onDispose() - the former will be called every code change, the latter when the root is stopped or the reference deleted. If the reference is AutoCloseable then it will be closed automatically on disposal by default.

Use eg.

@Inject Ref<List<String>> strings;

public void setup() {
    strings.apply(l -> {
        if (l.isEmpty()) {
            l.add("A String");
    List<String> lst = strings.get(); // same list across code changes

See the Javadoc for Ref<T> included with the IDE for the full range of features.