jess.interfaces

Also require('@jess/interfaces'). An interface is a plain Luau table an application's managed module returns as its interface, under the id its manifest gives it. When several provide one id, the last in load order wins, after its on.host.interfaceOverride kept what it wanted of the one before. What you get here is that effective table, frozen, in this domain's VM: no proxy, no copy. Interfaces exist once every managed module has loaded, in the application's entry and its handlers. A worker, another domain, jess run, and a command target have none.

jess.interfaces.get§

The effective implementation of id.

• Errors: interfaces.get: no package in this domain implements '<id>' (asked at <chunk>:<line>); it has <ids>; while managed modules are still loading, interfaces.get: interfaces are composed once every managed module has loaded; look '<id>' up in a handler or in the application's entry; in a domain no application loaded, interfaces.get: this domain has no interfaces; an application target composes them from its packages' [managed] modules; in a worker, interfaces.get: interfaces are the domain's own code's; a worker has none, so send it what it needs in a message; outside a domain, interfaces.get: needs a ScriptDomain.

--!strict
type Inventory = {
  getArmorType: (item: string) -> string,
  getWeight: (item: string) -> number,
}

local inventory: Inventory = require('@jess/interfaces').get('game.inventory')
print(`{inventory.getArmorType('cuirass')} cuirass, {inventory.getWeight('cuirass')} pounds`)

jess.interfaces.tryGet§

The same, or nil when no package provides id: for an interface that is optional. The other errors are get's; an application that isn't composed yet is a mistake, not an absence.

--!strict
local achievements = require('@jess/interfaces').tryGet('game.achievements')

if achievements then achievements.unlock('first-death') end

Related: Applications, jess.events.