Is the ordering of GetComponents reliable?

[ThySpektre]

Working around a limitation in Unity, it would be very helpful if GetComponents returns them in a reliable ordering. Is this guaranteed?

[Vryken]

I’m assuming the order of components returned is either the top-most to bottom-most on the GameObject, or the first-added to last-added component on the GameObject.

This is just a blind guess though; some testing would have to be done.

[lordofduct]

If it’s not documented as being guaranteed, then it’s not guaranteed.

It can change at any time in future versions of Unity, or change from target build to target build.

Unity - Scripting API: Component.GetComponents

It’s not documented as such, so no.

[Joe-Censored]

The order of returned components from GetComponents<> is the order they are in the inspector and is reliable. My own custom network API’s RPC system depends on this being the case, and I haven’t seen an instance of it yet failing to be so. (I’m currently still on 2018.2.21, so hopefully they haven’t broken this since then, but I doubt it)

[lordofduct]

I stand by my statement of ‘guarantee’, since guarantee implies that it has been stated as such by Unity. Which it hasn’t been.

But I have to say if you’re getting reliable results I’ll have to play around with it. The last time I ran tests on it was a few years ago when I was doing some ordering in my t&i system and I found different orders from build to build, especially between target platforms.

[Joe-Censored]

@lordofduct

I stand by my statement of ‘guarantee’, since guarantee implies that it has been stated as such by Unity. Which it hasn’t been.

But I have to say if you’re getting reliable results I’ll have to play around with it. The last time I ran tests on it was a few years ago when I was doing some ordering in my t&i system and I found different orders from build to build, especially between target platforms.

I believe in the long long ago it was not reliable. Not sure when that changed. I’m seeing the ordering is the same on Linux and Windows, but haven’t checked other platforms.

From the current documentation:

https://docs.unity3d.com/Manual/UsingTheInspector.html

@Unity Manual

The order you give to components in the Inspector window is the order you need to use when querying components in your user scripts. If you query the components programmatically, you’ll get the order you see in the Inspector.

Yeah they should put this on the GetComponents scripting reference page, instead of the last thing tagged onto the Inspector manual page, but there it is.

[lordofduct]

Nice find.

[Madgvox]

I think it’s worth mentioning that under ideal circumstances, you should probably attempt to design your program in such a way that the order of the components does not matter.

[palex-nx]

In order to develop new networking system they made this order reliable, but before it wasn’t. There was article about this in Unity blog.

[ThySpektre]

@Joe-Censored

I believe in the long long ago it was not reliable. Not sure when that changed. I’m seeing the ordering is the same on Linux and Windows, but haven’t checked other platforms.

From the current documentation:

https://docs.unity3d.com/Manual/UsingTheInspector.html

Yeah they should put this on the GetComponents scripting reference page, instead of the last thing tagged onto the Inspector manual page, but there it is.

Thanks for the info!

[ThySpektre]

@Madgvox

I think it’s worth mentioning that under ideal circumstances, you should probably attempt to design your program in such a way that the order of the components does not matter.

I’d prefer to go a completely different route with this system but cannot due to a limitation in Unity…but that’s an entire other can of worms.

[AntonioModer]

Note: GetComponent returns only the first matching component found on the GameObject on which it is called, and the order that the components are checked is not defined. Therefore, if there are more than one of the specified type that could match, and you need to find a specific one, you should use Component.GetComponents and check the list of components returned to identify the one you want.

(Unity - Scripting API: Component.GetComponent)

[Bunny83]

@Joe-Censored

I believe in the long long ago it was not reliable. Not sure when that changed.

Since the topic was already bumped, the order of the components was made reliable when the new audio filter system was introduced. That’s because audio filters use the order to “stack” themselfs. See the documentation:

The effects are applied by adding effect components to the object with the Audio Source or Audio Listener. The ordering of the components is important, since it reflects the order in which the effects will be applied to the source audio.

I think it was somewhere around Unity 5.2, so about 8 years ago.

[halley]

The reliable order was also necessary for nested Prefab enhancements in Unity 5; hence the warnings ever since that you could not re-order the components of a Prefab. (A limitation which may be overcome soon, likely with lots of bandages and paperclips and sealing wax.)

[lordofduct]

@Bunny83

I think it was somewhere around Unity 5.2, so about 8 years ago.

I think 5.2 was in 2017, so about 6 years ago.

5.0 was in 2015.

That time would also make sense relative to my results I was talking about in my old posts above. When I began developing that t&i system was pre-5.2.

[Bunny83]

@lordofduct

I think 5.2 was in 2017, so about 6 years ago.

5.0 was in 2015.

Yes, possible. I don’t have a track record of the Unity releases Though according to the release notes 5.2 was released on August 16, 2015. I’m not sure how reliable those dates are…

[lordofduct]

Agreed… I cant’ really keep track of all of it. I’m actually upset they’re going back to the numbering rather than year naming model. At least the year numbering SORT of helped in knowing when it came out (though of course LTS confuses that further).

For all I know it could have been late 2015. I google and got different results… but that just means different people are saying different things.