Type Checker and auto complete problem

[wispy island]

--!strict
-- @zyos73
-- 08/01/25

export type PublicChannel = {
    Type: "Public",
    Name: string,
    AutoJoin: boolean,
    Register: () -> any
}

export type PrivateChannel = {
    Type: "Private",
    Name: string,
    AllowedPlayers: {Player},
    Register: () -> any
}

export type Instances =
    PublicChannel |
    PrivateChannel

export type InstanceSelection =
    "PublicChannel" |
    "PrivateChannel"
    
export type MappedInstances = {
    PublicChannel : PublicChannel,
    PrivateChannel : PrivateChannel
}

return nil

New Function

--!strict
-- @zyos73
-- 08/01/25

-- Modules
local Package = script.Parent.Parent
local Types = require(Package.Types)

-- Types
type InstanceSelection = Types.InstanceSelection
type Instances = Types.Instances
type PublicChannel = Types.PublicChannel
type PrivateChannel = Types.PrivateChannel

-- Instances
local Instance = Package.Instances

local instanceMap = {
    PublicChannel = require(Package.Instances.PuplicChannel),
    PrivateChannel = require(Package.Instances.PrivateChannel)
}

local function New(instanceType : InstanceSelection) : Instance
    local instance = instanceMap[instanceType]()
    return instance
end

return New

Usage (No auto complete for newPrivateChannel.AllowedPlayers & newPublicChannel.AutoJoin)

--!strict
-- @zyos73
-- 08/01/25

-- Modules
local TextChatServiceV2 = require(game.ServerScriptService.TextChatServiceV2)
local Types = require(game.ServerScriptService.TextChatServiceV2.Types)

local player = game.Players:WaitForChild("Zyozok")

local newPrivateChannel = TextChatServiceV2.New("PrivateChannel")
newPrivateChannel.AllowedPlayers = {player}
newPrivateChannel.Register()

local newPuplicChannel = TextChatServiceV2.New("PublicChannel")
newPuplicChannel.Register()

So the problem im having is that the type checker cant tell what type im returning in the new() function I was thinking about forcing the type to be Public- or Private-Channel at the very end, for this to work I need to convert the string im getting into a type tho, is that possible? Also if theres another solution for this while not changing the function and setting the type im the Usage Script tell me!

I tried the dynamic type thingy with the new type solver already thats pretty buggy

[hot niche]

puplic

[hot niche]

i don't understand this

[wispy island]

[hot niche]

ohh

why not make separate functions for public and private channel?

[wispy island]

cause I want to handle everything with ``.New("type")likeInstance.New("type")` does

[hot niche]

i really don't know why you would do that

[wispy island]

cause I can seperate things
-> New --creates new Instances
-> etc. etc.

else it would be
-> NewPublicChannel
-> NewPrivateChannel

I dont want this many functions under the main API

[solar slate]

PublicChannel = require(Package.Instances.PuplicChannel)

[solar slate]

its because you are returning a union type and you aren't refining it

[wispy island]

no shit

[solar slate]

export type Instances =
    PublicChannel |
    PrivateChannel```

use template maybe

[wispy island]

wdym

local function New<T>(instanceType : T & InstanceSelection) : T & Instances
    return MappedInstances[instanceType]
end

if you mean this I tried this and it works but I would have to define the type everytime i want to create a new channel

[solar slate]

that doesn't look right

T & InstanceSelection ?

[wispy island]

local function New<T>(instanceType : InstanceSelection) : T & Instances
    assert(MappedInstances[instanceType], `Type not found`)
    return MappedInstances[instanceType]
end

mb this works

I dont rlly understand these templates yet

local newPrivateChannel : Types.PrivateChannel = TextChatServiceV2.New("PrivateChannel")
newPrivateChannel.AllowedPlayers = {}
newPrivateChannel.Register()

local newPublicChannel : Types.PublicChannel = TextChatServiceV2.New("PublicChannel")
newPublicChannel.AutoJoin = false
newPublicChannel.Register()

Wehn doing this I need to define the Type beforehand which I also don't really want to use wehn theres a better solution

[solar slate]

the signature would just be New<T>(instanceType:InstanceSelection):T

you can generalize but i'm not sure how instance.new does it

[wispy island]

how can it be so hard to create the similair api to Instance.new("type")🥀

[wispy island]

yeah

[solar slate]

aka make a baseclass for the channel then type refine so you get most of the properties for free

[wispy island]

wdym

how would a baseclass look like

[solar slate]

wait no the union should already do that, it's been a while for me

[wispy island]

yeah I get like Type, Name and Register to auto complete just not the 2 diffrent properties

Ive been at trying to do this for 4-5h now I don't think ima find a solution for this tbf

[solar slate]

type refinement would work too

but its not quite exactly like instance.new

this might work https://devforum.roblox.com/t/how-to-trick-luau-typechecking-into-returning-instance-classes-based-on-function-arguments/1787282/15

[wispy island]

mm alr ima read ts

thanks

[solar slate]

this looks interesting

type ChannelInstances = {
  PublicChannel:PublicChannel;
  PrivateChannel:PrivateChannel;
}
local function New(instanceType: keyof<ChannelInstances>)
  local r:index<ChannelInstances, typeof(instanceType)> = MappedInstances[instanceType]()
  return r
end
local priv=New("PrivateChannel")
local pub=New("PublicChannel")
-- autocompleted types?
``` i can't test this in studio

sauce: https://devforum.roblox.com/t/how-to-trick-luau-typechecking-into-returning-instance-classes-based-on-function-arguments/1787282/25

[wispy island]

Types

--!strict
-- @zyos73
-- 08/01/25

export type PublicChannel = {
    Type: "Public",
    Name: string,
    AutoJoin: boolean,
    Register: () -> any
}

export type PrivateChannel = {
    Type: "Private",
    Name: string,
    AllowedPlayers: {Player},
    Register: () -> any
}

export type Instances =
    PublicChannel |
    PrivateChannel

export type InstanceSelection =
    "PublicChannel" |
    "PrivateChannel"
    
export type MappedInstances = {
    PublicChannel : PublicChannel,
    PrivateChannel : PrivateChannel
}

return nil

New Function

--!strict
-- @zyos73
-- 08/01/25

-- Modules
local Package = script.Parent.Parent
local Types = require(Package.Types)
local InstanceFunctions = require(script.InstanceFunctions)

-- Types
type MappendInstances =  Types.MappedInstances
type InstanceSelection = Types.InstanceSelection
type Instances = Types.Instances
type PublicChannel = Types.PublicChannel
type PrivateChannel = Types.PrivateChannel

-- Instances
local Instance = Package.Instances



local function New(instanceType : keyof<MappendInstances>)
    assert(InstanceFunctions[instanceType], `Instance not found`)
    local instance: index<MappendInstances, typeof(instanceType)> = InstanceFunctions[instanceType]
    return instance
end

return New

Usage

--!strict
-- @zyos73
-- 08/01/25

-- Modules
local TextChatServiceV2 = require(game.ServerScriptService.TextChatServiceV2)
local Types = require(game.ServerScriptService.TextChatServiceV2.Types)

local player = game.Players:WaitForChild("Zyozok")

local newPrivateChannel = TextChatServiceV2.New("PrivateChannel")
newPrivateChannel.AllowedPlayers = {}
newPrivateChannel.Register()

local newPublicChannel = TextChatServiceV2.New("PublicChannel")
newPublicChannel.AutoJoin = false
newPublicChannel.Register()

Sadly it still doesnt detect .AllowedPlayers and .AutoJoin