A better way to associate metadata with objects such as Players

[dktapps]

Description

Currently it's difficult to store data which is associated with, for example, a Player, which will not outlive the player.

Current methods used

• Plugins keep their own hashmap of some unique identifier -> whatever data
  • Problem: The plugin must clean up after itself when the player quits. If it does not, memory will be leaked.
• MetadataStore: I don't think anyone actually uses this overengineered piece of cargo-cult garbage. MetadataStore in Bukkit is designed to deal with this problem.
  • Problem: Overengineered to the point of being unusably inconvenient.
  • Problem: Objects associated with a particular Metadatable are not cleaned up when the Metadatable is disposed, making it effectively useless for this purpose.
• Magic fields on players
  • Problem: this was never really supported API and is broken as of 3.5.6 (see $e->getPlayer()->$property = internal error #2732).
  • Problem: Different plugins' data may collide.
• Extra tags in Entity->namedtag
  • Problem: Again, this is not really supported API and is no longer possible as of latest 4.0 dev builds since NBT is no longer retained at runtime.
  • Problem: It's not possible to store non-scalar items in this manner.
  • Problem: Different plugins' data may collide.
  • Problem: Data ends up getting saved to disk, which might not be desirable.

[dktapps]

This is no longer needed as PHP's WeakMap can now be used for this purpose.