Pure Lua Signal

Signal.lua

--[[
    Signal class in pure Lua.
    Based on Roblox's BindableEvents.

    Signal.new(): Signal
    -- Creates a new Signal object

    Signal:Connect(Callback: function): SignalConnection
    -- Binds a function to invoke when the Signal is fired

    SignalConnection:Disconnect(): nil
    -- Unbinds the previously bound function

    Signal:Fire(...args: any): nil
    -- Invokes bound functions, passing the given arguments

    Signal:Destroy(): nil
    -- Unbinds all functions, and prevents the Signal from
        being fired/connected to again
--]]

local Signal = {}; do
    math.randomseed(os.time())
    Signal.__index = Signal
    
    function Signal.new()
        local self = setmetatable({}, Signal)
        self.__callbacks = {}
        
        return self
    end
    
    function Signal:Connect(Callback)
        local this = self
        
        local CallbackId = math.random(1000000, 9999999)
        this.__callbacks[CallbackId] = Callback
        
        return {
            Disconnect = function()
                this.__callbacks[CallbackId] = nil
            end
        }
    end
    
    function Signal:Fire(...)
        for _, callback in next, self.__callbacks do
            coroutine.wrap(callback)(...)
        end
    end
    
    function Signal:Destroy()
        for key, _ in next, self.__callbacks do
            self.__callbacks[key] = nil
        end
        
        self = setmetatable({})
        self = nil
    end
end

Signal.min.lua

local Signal={}do math.randomseed(os.time())Signal.__index=Signal;function Signal.new()local self=setmetatable({},Signal)self.__callbacks={}return self end;function Signal:Connect(b)local c=self;local d=math.random(1000000,9999999)c.__callbacks[d]=b;return{Disconnect=function()c.__callbacks[d]=nil end}end;function Signal:Fire(...)for e,f in next,self.__callbacks do coroutine.wrap(f)(...)end end;function Signal:Destroy()for g,e in next,self.__callbacks do self.__callbacks[g]=nil;end;self=setmetatable({})self=nil end end

local TestEvent = Signal.new()

local TestEventConn; do
    TestEventConn = TestEvent:Connect(function(text)
        print("> Signal fired:", text)
        TestEventConn:Disconnect()
    end)
end

TestEvent:Fire("Hello, world!") --> Will print: "> Signal fired: Hello, world!"
TestEvent:Fire("Bye, world!") --> Won't fire, as it was disconnected when it was first fired