$ref & $unref

5min
The ref and out keywords in C# are used when passing references to variables or structures to methods.
In TypeScript, these keywords are not available, but in ZEPETOScript, you can achieve similar functionality using $ref and $unref.
Functions
Description
$ref(x?:T):$Ref
Creates a reference for a parameter
$unref(x:$Ref):T
Releases the reference of a parameter and returns the original value
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For the example, let's set up a Scene as follows:
Add a 3D object, Cube, to the Scene.
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In the Inspector for the added Cube, click "Add Component" and add a Rigidbody.
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Add an Empty GameObject to the Scene.
Write the RefSample script below and add it to the GameObject created in step 3.
TypeScript
import { GameObject, Rigidbody } from 'UnityEngine'
import { ZepetoScriptBehaviour } from 'ZEPETO.Script'
import TestScript from './TestScript';
 
export default class RefSample extends ZepetoScriptBehaviour {
 
    Start() {   
        // Get the GameObject named "Cube"
        const testObject = GameObject.Find("Cube");
         
        // Get the Rigidbody Component from the "Cube" Object
        const testComponent = GameObject.Find("Cube").GetComponent<Rigidbody>();
         
        // Get the TestScript Component from the "Cube" Object
        const testScript = GameObject.Find("Cube").GetComponent<TestScript>();
 
        // Create references to the components and object
        let tempObj = $ref(testObject);
        let tempComponent = $ref(testComponent);
        let tempScript = $ref(testScript);
 
        // Check if the Rigidbody component is not null
        if(tempComponent != null) {
            // Access the actual value of that reference
            let component = $unref(tempComponent);
            console.log(`Component Name : ${component}`);
        }
 
        // Check if the TestScript component is not null
        if(tempScript != null) {
            // Access the actual value of that reference
            let script = $unref(tempScript);
            script.DoTest();
        }
 
        // Check if the GameObject reference is not null
        if(tempObj != null) {
            // Access the actual value of that reference
            let objName = $unref(tempObj);
            console.log(`tempObj Name : ${objName.name}`);
        }
    }
}
import { GameObject, Rigidbody } from 'UnityEngine'
import { ZepetoScriptBehaviour } from 'ZEPETO.Script'
import TestScript from './TestScript';
 
export default class RefSample extends ZepetoScriptBehaviour {
 
    Start() {   
        // Get the GameObject named "Cube"
        const testObject = GameObject.Find("Cube");
         
        // Get the Rigidbody Component from the "Cube" Object
        const testComponent = GameObject.Find("Cube").GetComponent<Rigidbody>();
         
        // Get the TestScript Component from the "Cube" Object
        const testScript = GameObject.Find("Cube").GetComponent<TestScript>();
 
        // Create references to the components and object
        let tempObj = $ref(testObject);
        let tempComponent = $ref(testComponent);
        let tempScript = $ref(testScript);
 
        // Check if the Rigidbody component is not null
        if(tempComponent != null) {
            // Access the actual value of that reference
            let component = $unref(tempComponent);
            console.log(`Component Name : ${component}`);
        }
 
        // Check if the TestScript component is not null
        if(tempScript != null) {
            // Access the actual value of that reference
            let script = $unref(tempScript);
            script.DoTest();
        }
 
        // Check if the GameObject reference is not null
        if(tempObj != null) {
            // Access the actual value of that reference
            let objName = $unref(tempObj);
            console.log(`tempObj Name : ${objName.name}`);
        }
    }
}
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Create another ZEPETOScript and write the TestScript below.
TypeScript
import { ZepetoScriptBehaviour } from 'ZEPETO.Script'
 
export default class TestScript extends ZepetoScriptBehaviour {
 
    DoTest() {   
        console.log(`TestScript's DoTest() is executed.`);
    }
}
import { ZepetoScriptBehaviour } from 'ZEPETO.Script'
 
export default class TestScript extends ZepetoScriptBehaviour {
 
    DoTest() {   
        console.log(`TestScript's DoTest() is executed.`);
    }
}
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Drag and connect TestScript to the Cube's Inspector.
Click the [▶︎(play)] button to observe the results.
You can check the success of referencing objects, Rigidbody components, and ZEPETOScript components in the console log window.
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Functions	Description
$ref(x?:T):$Ref	Creates a reference for a parameter
$unref(x:$Ref):T	Releases the reference of a parameter and returns the original value
Updated 10 Oct 2024
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