Export and import IOTypes so usages look like PropertyIO instead of Property.PropertyIO

[samreid]

When we designed the IO Type system, we did not utilize the fact that a file could have multiple exports. But it seems like a lot of usage sites would be easier to read and write if IO types could be written like Vector2IO or PropertyIO instead of Vector2.Vector2IO and Property.PropertyIO.

Tagging @pixelzoom and @zepumph so they aware this is coming up.

[pixelzoom]

Usages like Vector2.Vector2IO don't bother me. And in fact I think it's preferrable (and necessary) if you want to save/restore private parts of the core type. So if you're planning to change that, let's chat first.

[pixelzoom]

Oh... Maybe you're saying that Vector2.ts should simply add an export for Vector2.Vector2IO?

[samreid]

Yes, adding an export. I'll add a commit momentarily demonstrating it for Property.PropertyIO.

[samreid]

The commits show the proposal for exporting PropertyIO. @pixelzoom does that look good to you?

[pixelzoom]

I'm not sure that PropertyIO was a good choice as an example. Or maybe it was a good choice, to demonstrate problems with this proposal.

(1) PropertyIO is not defined in Property.ts, and is in fact associated with core type ReadOnlyProperty. So it violates the PhET naming conventions, and was therefore confusing. If conventions had been followed, I should have been looking at replacements of Property.PropertyIO with PropertyIO.

(2) Most IO Types I've seen are declared like public static readonly SomethingIO =. PropertyIO is declared as public static PropertyIO<T, StateType>( parameterType: IOType<T, StateType> ): IOType {...}. Maybe that's responsible for (3).

(3) The additional export requires an eslint-disable. Will that be needed for all IOType exports? Why is it needed for this one?

export const PropertyIO = ReadOnlyProperty.PropertyIO; // eslint-disable-line bad-text

That said...

Is this the general convention that you're proposing?

// definition
export default class MyType {
   public static readonly MyTypeIO = ...;
}

export const MyTypeIO = MyType.MyTypeIO;

// usage - either, at developer discretion
phetioValueType: MyTypeIO
phetioValueType: MyType.MyTypeIO

If so...

• I see little value in this, especially if IOTypes are a public static readonly property of their core type.
• It allows developers to violate conventions, as has been done with PropertyIO.
• I'll (and other devs?) will likely spend time remembering the form of the additional export1, or forget to include it.

So my vote for this is proposal is "no".

[samreid]

I agree, having IO types be declared as a public static readonly property of the core type seems like the most important part, and it is not necessary to provide a shorthand for usage sites. Most commits will auto-revert, but I'll need to manually revert axon and energy-forms-and-changes. Coming up soon...

[samreid]

Thanks, I reverted the changes for this issue and elaborated on a new side issue https://github.com/phetsims/axon/issues/429. @pixelzoom can this issue be closed?

[pixelzoom]

👍🏻 closing.