C# Overridable Methods

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Maybe this is a silly question, so apologies up front if it is.

If some methods (say FixedUpdate) are overridable methods, why don't I see their virtual declarations anywhere in the metadata for the hierarchy chain (MonoBehaviour > Behaviour > Component > Object)?

Answer 1

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Answer by Mike 3 · Jul 31, 2010 at 03:18 PM

They aren't actually overridable. What happens is the engine uses reflection to find them all in your scripts at creation, then invokes the stored references at runtime

It also means that scripts that don't have an Update (or any other) method don't need to have it called at runtime - that means it's a bit faster as it doesn't have to call every function in every script from the native engine

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qJake · Jul 31, 2010 at 06:26 PM 2

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Not to mention you don't need to call base.Update(); either ;)

NateJC · Aug 14, 2015 at 09:56 PM 0

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You say that calling base.Update(); is unnecessary. But what if I want to control if and when it calls base.Update();? Is this not possible?

Answer 2

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Answer by Lucas Meijer 1 · Jul 31, 2010 at 11:05 PM

This is a bit of a design mistake on our end. They are called trough reflection, so we only call the methods on objects that actually have the method. We should have made the methods be virtual in the MonoBehaviour basetype though, so you get nicer autocompletion etc. I would love to correct this situation, but the problem is that if we do, we would break pretty much all c# scripts out there, as you'd have to rewrite

void Update()
{
}

to

override void Update()
{
}

maybe we'll do it one day when we have the capability to automatically make changes like these for you, but that day is not in the near future

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Mike 3 · Jul 31, 2010 at 11:45 PM 1

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If they were abstract, they'd have to be implemented though. All of them. That'd make people either get very annoyed at having to implement them every time, or force them to write their own base script which implements all of them as virtual. Either way, it would negate any ability to skip updating functions for speed

Lucas Meijer 1 · Aug 01, 2010 at 09:17 AM 0

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Hey Mike, thanks, I fixed the post to say abstract->virtual. It would not negate any ability to skip updating for speed, as we could still use reflection to see which classes do override the method, and which don't.

Mike 3 · Aug 01, 2010 at 10:13 AM 0

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Indeed, with virtual methods. With abstract (which I was complaining about), not a chance :D

Maulkye · Aug 03, 2010 at 08:58 PM 0

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Ahh, ok. Thanks!

jc_lvngstn · Sep 27, 2012 at 07:05 PM 1

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No advantage of virtual methods over reflection? I would think performance would be one. Another very real advantage is, when you use Visual Studio (especially with Resharper), you can very quickly see what methods you can override.

It's annoying to have to go back to the scripting reference just to see what that mouse over enter/exit method name is.

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C# Overridable Methods

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