@quenty/servicebag

ServiceBag

Service providing mechanisms for Nevermore

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Installation

npm install @quenty/servicebag --save

Goals

• Remove requirement for many services to be loaded
• Make installing new modules really easy
• Make testing easier
• Reduce maintaince costs
• Explicitly declare service pattern
• Force declaration of service usage
• Make it easy to trace service dependencies

Requirements

• Initialize dependent services using :Init()
• Start dependent services using :Start()
• Retrieve services is easy
• Don't have to list off every service in the game
• Services don't load until we ask them to
• Circular dependencies allowed

Like-to-have

• Dependency injection for tests
• Works with type system GetService<IService>()
• Async initialization (return promises instead of blocking)
• Dependency graph safe (i.e. recursive service requirement )
• Services are protected from another service erroring

Stretch goals

• Handles services for actors (remove global code)

Ideas

• Inject a ServiceBag

Rules

1. Each service will be identified by its module
2. Each service will be initialized once
3. If we require a service, we will not have to declare subservices

-- Main script
local serviceBag = require("ServiceBag").new()

serviceBag:AddService(require("TransparencyService"))

serviceBag:Init()
serviceBag:Start()

-- Other script
local TransparencyService = require("TransparencyService") -- force declaration at top

local TestClass = {}
TestClass.ClassName = "TestClass"
TestClass.__index = TestClass

function TestClass.new(serviceBag)
	local self = setmetatable({}, TestClass)

	self._serviceProvider = assert(serviceBag, "No serviceBag")

	self._transparencyService = self._serviceProvider:GetRequiredService(TransparencyService)
	
	return self
end

return TestClass

local DialogPane = setmetatable({}, BasicPane)
DialogPane.ClassName = "DialogPane"
DialogPane.__index = DialogPane

function DialogPane.new(serviceBag)
  local self = setmetatable(BasicPane.new(serviceBag:GetService(DialogTemplatesClient):Clone("DialogPaneTemplate")), DialogPane)

  self._theme = Instance.new("StringValue")
  self._theme.Value = "Light"
  self._maid:GiveTask(self._theme)

  self._dialogInput = DialogInput.new()
  self._maid:GiveTask(self._dialogInput)