The set inheritance modification problem about nyan

[heinezen]

I think the solution with annotations is the better one, since using inheritance could get convoluted for units with many different abilities. It's probably easier to explain, too. I would just suggest switching the symbols for the first and second operation as @ and + are already used in different contexts in nyan.

Using @ for the 2nd case instead of the 1st one would be better because this is more in line with @ signifying the override/replacement of an operator when its placed in front of it. In this context, it would signify the "override" of a parent with a child object which is very similar to the other use of @.

+ already appears in an entirely different context (patching inheritance), so I would avoid using it here. Maybe $, ~ or ? are better?

[MichaHoffmann]

Since this seems to be a syntactical problem, how about declaring the 3 possibilities like python decorators? i.e

Unit(Entity):
    @replacedByChild
    Move(Ability):
        speed = 1.0
    abilities += {Move}

Villager(Unit):
    VillagerMove(Unit.Move):
        speed = 10.0
    # this now automatically replaces `Move` with `VillagerMove`
    abilities += {VillagerMove}

[TheJJ]

(Sorry for the very delayed reply.....) Unfortunately it's not just syntactic, we are changing the set semantics here and need to configure that syntactically. Using decorators (at least to annotate the object itself) is probably not such a good choice since in a different set, the rule may not apply. So this needs to be a configuration for each set.

[TheJJ]

@heinezen and I just found a solution for this.
The realization was that we need both directions for these modifications:

• Inserting a specialized object into the set should replace all parents
• Removing a parent object (may not be in the set itself) should remove all children
  This means the inheritance hierarchy should be enforced. This can be done by configuring the set to ensure the inheritance hierarchy by overwrites.
  Example:

Entity:
    abilities : set(Ability, hierarchy_overwrite=True) = {}

Unit(Entity):
    Move(Ability):
        speed = 1.0
    abilities += {Move}

Villager(Unit):
    VillagerMove(Unit.Move):
        speed = 10.0
    # VillagerMove replaces Move, since the set was configured with hierarchy_overwrite!
    abilities += {VillagerMove}

Regarding "Where is the border", i.e. when inserting a child, up until what level should parents be purged from the set? The "maximum anchestor" is the set's member type. In the above example, this means the VillagerMove insertion removes all parents in the inheritance line between Ability and VillagerMove, thus Move is replaced by VillagerMove.

This would be @mic-e's "ne andere magic" from his brainstorm in 2018 :) (or actually a "keyword" in the set creation!)