Best way to reference a prefab

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Let me start by saying that the differences between GameObject and Transform are pretty clear to me so please don't give me an answer of that type.

I noticed that, from within a script, when I want to access a prefab I can achieve it in both ways:

public GameObject prefab;    // This works
...
Instantiate(prefab);
...

public Transform prefab;    // This works too
...
Instantiate(prefab.gameObject);
...

I noticed that no matter which I use I can pass a prefab from the unity editor and do anything I want with it later on, using the appropriate functions.

Now my question is, is any of these two incorrect in any way? Can any of them lead to a weird behaviour? Is there a "best coding practice" that defines how to reference a prefab? Finally does it have any difference performance-wise (In the way unity treats the reference or something)?

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Answer by Hellium · Oct 17, 2017 at 07:18 PM

There is no "best way".

The advantage to reference a Component (such as Transform), is that you can force your designer to do provide a gameobject holding the given component. For example : public Rigidbody prefab if you want to have the instance with a Rigidbody.

If you only declare public GameObject prefab, your designer could potentially put any gameobject he wants.

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KostasBs · Oct 17, 2017 at 07:32 PM 0

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When you pass the prefab in the script at the game editor, doesnt unity apply any conversions? That was my first thought because in order for the object to adapt to both some things should happen in the background. From your answer I understand that this gives $$anonymous$$imal performance overhead, is that correct? I know its a small detail but sometimes these things bug you :) and also my project relies heavily on prefab instantiation so any small difference may improve/decrease performance.

Hellium KostasBs · Oct 17, 2017 at 07:48 PM 2

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I don't know what Unity does in the background, but I don't think it does any "conversion". When a gameobject is dragged to the public field, Unity just checks if the component is attached to it.

Yes, you will have increase a little bit the performance, but I don't think it will be noticeable. It's mostly used to make things easier for your designers and prevent some mistakes.

StormMuller · Oct 17, 2017 at 08:28 PM 1

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Yea all components hold a reference to the gameobject they're attached to. So calling transform.gameObject has no performance hit. But there are some good practices you might want to follow. If you want to really decouple your design. Then use GameObject ins$$anonymous$$d of Transform as it is more abstract. Unity by default will force you to have a transform for each gameobject in the scene. But lets say you publicly exposed a rigidBody ins$$anonymous$$d of a gameobject. and later on you create a player that uses a playerController ins$$anonymous$$d of a rigidbody you would have to restructure your code to accommodate the change.

If you wanted to force the use of a component you could use rigidbody ins$$anonymous$$d of gameobject.

What I prefer doing is using inheritance and abstract classes to force the use of a specific type. This allows me to unit test my code. (Unity won't show interface types in the inspector, which sucks. But there are work arounds.)

KostasBs StormMuller · Oct 17, 2017 at 09:05 PM 0

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Usefull information about Component enforcement and unit testing, thanks a lot :)

Best way to reference a prefab

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