Locale priority, or other ways to do invisible objects

I want certain objects to be listed or not listed depending on which person the player currently is.
This is what I’ve tried:

Every turn: If the player is Sarah: set locale priority of the blue vase to 0; set locale priority of the sporting trophy to 1; If the player is Bob: set locale priority of the blue vase to 1; set locale priority of the sporting trophy to 0;

I want only one of those objects to be obvious, but currently both items are still listed in the room description. Just removing the item is not a good solution, because I still need the player to be able to interact with the item once they know it is there from having played the other character.

To make an object not appear in a location:

Rule for writing a paragraph about the table:
	now the table is mentioned.

You can make that conditional, of course, by adding a “…when the player is Bob” clause to the rule.

Thanks!

Interestingly this doesn’t seem to work when the objects are supported by something (I guess because then they become part of the supporter’s description?)… so I just got rid of the shelf they were on.

I think that “set the locale priority of the blue vase to 0” and “now the blue vase is mentioned” basically do the same thing under the hood, as per this part of the Standard Rules:

To set the/-- locale priority of (O - an object) to (N - a number): if O is a thing: if N <= 0, now O is mentioned; if there is a notable-object of O in the Table of Locale Priorities: choose row with a notable-object of O in the Table of Locale Priorities; if N <= 0, blank out the whole row; otherwise now the locale description priority entry is N; otherwise: if N is greater than 0: choose a blank row in the Table of Locale Priorities; now the notable-object entry is O; now the locale description priority entry is N;

Yes. (Since the supporter is more directly in the location it is described before the things that are on it, and, when it’s at it, Inform also describes the things on that supporter.) But that just means that the argument to the rule needs to be the supporter rather than the thing you you want not to show up on it:

The place is a room.
The shelf is a supporter in place.
On the shelf are  a blue vase and a sporting trophy.

For writing a paragraph about the shelf:
	now the vase is mentioned.

You could also tweak the “describe what’s on scenery supporters” rule (possibly not its full name).