Recreation of Roblox RBXScriptSignals in pure Lua

A_RawSignal.lua

--[[
    RawSignal by csqrl (ClockworkSquirrel)
    Version: 0.0.2
    License: MIT

    Originally uploaded to Dcoder.

    Documentation:
        Signal:
            Methods:
                Signal.new(): RawSignal

        RawSignal:
            Methods:
                RawSignal:Connect(Callback: function): DisconnectionTable
                RawSignal:Fire(...): void
                RawSignal:Destroy(): void

        DisconnectionTable:
            Methods:
                DisconnectionTable:Disconnect(): void
--]]
local Signal = {}

Signal.__index = Signal

function Signal.new()
    local self = setmetatable({}, Signal)
    
    self.__callbackInt = 0
    self.__callbacks = {}

    return self
end

function Signal:Connect(Callback)
    if self._destroyed then
       error("Signal has been destroyed", 2) 
    end
    
    local this = self

    this.__callbackInt = this.__callbackInt + 1
    
    local CallbackId = tostring(this.__callbackInt)
    this.__callbacks[CallbackId] = Callback

    return {
        Disconnect = function()
            this.__callbacks[CallbackId] = nil
        end
    }
end

function Signal:Fire(...)
    if self._destroyed then
        error("Signal has been destroyed", 2)
    end
    
    for _, callback in next, self.__callbacks do
        coroutine.wrap(callback)(...)
    end
end

function Signal:Destroy()
    self._destroyed = true
    
    for key, _ in next, self.__callbacks do
        self.__callbacks[key] = nil
    end

    for key, _ in pairs(self) do
        self[key] = nil
    end
end

return Signal

LICENSE

MIT License
 
Copyright (c) 2020 csqrl (a.k.a. ClockworkSquirrel)
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software without modification.
 
THE SOFTWARE IS PROVIDED "AS IS" BY CSQRL, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHOR
(CSQRL), CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.