Hive clusters
Much of the logic in Overmind is implemented in hive cluster components, which represent a way to group related structures, creeps, and functionalities that serve a similar purpose and are (usually) spatially close together. Hive clusters can also submit resource requests to the colony overlord for delivery via link or hauler, can directly control their workers, can group together other clusters, and allow for a much more condensed code.
This is an example of one of my room layouts:
In this example, there are four hive clusters: a hatchery, a command center, a mining site, and an upgrade site. Each cluster usually has its own workers, which also have a reference to their assigned cluster.
The following section is deprecated. Objectives have now been removed, with most of their functionality refactored into Overlords.
Hive clusters allow you to subdivide objectives. Most creeps in Overmind don't have much internal logic and simply act as agents to complete prioritized objectives given to them by the colony overlord. Objectives are wrappers that dispense Task objects and are contained in an ObjectiveGroup, which can be owned by an overlord or a hive cluster; this allows you to limit the objectives that creeps are allowed to request to the ones within their assigned hive cluster. Some clusters, like the command center, don't use objectives and instead assume direct control of their workers.