Guice pattern for long lived dynamic 1:1 relationships?

[Ryan Leach]

In Minecraft, specifically SpongeAPI, There are a series of Worlds that are
simulated in game.

These worlds are generally in an update cycle known as 'ticking' that world.

Worlds are generally loaded at startup, and unloaded on shutdown, but can
have repeating life cycles on the client, where someone might return to the
main menu, then load up a new game save loading new worlds.

On the server, worlds can be added or removed by the admins while the game
is running.

If I have Services(onStart,onEnd,onTick) and virtual game entities (not
true entities that live in the world, but are simulated like they are by
the services that depend on world)

And SpongeAPI provides World load/unload events.

What would be the best strategy using Guice to manage dependencies on
worlds?

If I listen for the world load/unload events, I have the world needed
pretty easily to do the DI manually for the services, but under Guice I'm
not sure how to correctly bind classes that need a world, to be using the
correct world?

Most Guice tutorials I've seen handle Request scopes, or application
bootup, but never really multiple anonymous dependencies with a 1:1
relationship, that can be dynamically loaded / unloaded.

Or am I right in thinking this needs to be handled manually, and all Guice
can do to help in this situation, is inject the world that I explicitly
provide in a ReentrantScope (https://github.com/timboudreau/scopes) and
somehow keep that scope around for children of the service?

[Stephan Classen]

Scopes are surely a way to handle this situation. But Scopes are also
hard to get right and they introduce a little "magic" because you need
to know that a dependency is scoped. Because if you cache the instance
you get from guice in a field it may not be the one you expect at a
later state...

Therefore I like to make such things a bit more explicit. In your case I
would create a Class called CurrentWorlds. Make that class a singleton
and have it implement the following 3 methods:
- add(World world)
- remove(World world)
- Collection<World> get()

In you EventListener you can then add and remove worlds as they get
loaded and unloaded and in your regular code you can always get the
current worlds which is the collection of worlds loaded at that very moment.

Post by Ryan Leach
In Minecraft, specifically SpongeAPI, There are a series of Worlds
that are simulated in game.
These worlds are generally in an update cycle known as 'ticking' that world.
Worlds are generally loaded at startup, and unloaded on shutdown, but
can have repeating life cycles on the client, where someone might
return to the main menu, then load up a new game save loading new worlds.
On the server, worlds can be added or removed by the admins while the
game is running.
If I have Services(onStart,onEnd,onTick) and virtual game entities
(not true entities that live in the world, but are simulated like they
are by the services that depend on world)
And SpongeAPI provides World load/unload events.
What would be the best strategy using Guice to manage dependencies on
worlds?
If I listen for the world load/unload events, I have the world needed
pretty easily to do the DI manually for the services, but under Guice
I'm not sure how to correctly bind classes that need a world, to be
using the correct world?
Most Guice tutorials I've seen handle Request scopes, or application
bootup, but never really multiple anonymous dependencies with a 1:1
relationship, that can be dynamically loaded / unloaded.
Or am I right in thinking this needs to be handled manually, and all
Guice can do to help in this situation, is inject the world that I
explicitly provide in a ReentrantScope
(https://github.com/timboudreau/scopes) and somehow keep that scope
around for children of the service?
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