Hatchery: build() vs refresh()

Hatchery.ts

import {$} from '../caching/GlobalCache';

export class Hatchery extends HiveCluster {

    // constructor gets run only on ticks with build() phase
    constructor(colony: Colony, headSpawn: StructureSpawn) {
        super(colony, headSpawn, 'hatchery');
        this.memory = Mem.wrap(this.colony.memory, 'hatchery', HatcheryMemoryDefaults, true);
        // Register physical structure components
        this.spawns = colony.spawns;
        this.availableSpawns = _.filter(this.spawns, spawn => !spawn.spawning);
        this.extensions = colony.extensions;
        this.towers = colony.commandCenter ? _.difference(colony.towers, colony.commandCenter.towers) : colony.towers;
        this.battery = _.first(_.filter(this.room.containers, cont => insideBunkerBounds(cont.pos, this.colony)));
        $.set(this, 'energyStructures', () => this.computeEnergyStructures());
    }

    // refresh() gets run on all other ticks
    refresh() {
        this.memory = Mem.wrap(this.colony.memory, 'hatchery', HatcheryMemoryDefaults, true); // refresh memory object
        // refresh room and structure properties for next tick
        $.refreshRoom(this);
        $.refresh(this, 'spawns', 'extensions', 'energyStructures', 'link', 'towers', 'battery');
        this.availableSpawns = _.filter(this.spawns, spawn => !spawn.spawning); // recalculate available spawns
    }
    
    // ...
    
}