need a better API for specifying "null is a valid value"

[pixelzoom]

If null is a valid value for a Property, then using type-specific Properties is out of the question, and I have to resort to this boilerplate:

const someProperty = new Property( initialValue, {
  isValidValue:  value => ( value instanceof SomeType || value === null ),
  phetioType: NullableIO( SomeTypeIO )
} );

I see 165 occurrences of regex Property.<.*\|null in PhET code, so this is a common scenario.

Can validator.js and Property APIs support a simple way of specifying that null is a valid value? Something that makes the above boilerplate unnecessary?

[samreid]

I believe @pixelzoom proposed valueType: [SomeType, null] for cases like that. @zepumph or @pixelzoom does that ring a bell?

[pixelzoom]

That rings a bell, but I can't find the issue where I proposed that (if one exists).

[pixelzoom]

Ah, here it is: #228 (comment). So I'm going to close this as a duplicate issue.