Can Anybody Explain Why You Need To Return The Function in Line 4?
I am trying to analyze one of the scripts in the ModuleScript section of the Roblox wiki. However, after looking at this for a while, I cannot seem to grasp on why you need to return the function... I understand everything else perfectly. The 'func' variable would just be a function of a touch script which requires the debounce (second script)
Can someone also care to explain how I can use this in other situations so I can learn about module scripts?
ModuleScript
function debounce(func)
local running = false
return function(...) -- <----- explain this!!
if not running then
running = true
func(...) -- call the function used in the touch script
running = false -- after the "wait 3" in touch script finishes the function ends and running = false."
end
end
end
return debounce
TouchScript
debounce = require(game.ServerStorage.Debounce)
script.Parent.Touched:connect(debounce(function(hit)
if hit and game.Players:GetPlayerFromCharacter(hit.Parent) and hit.Parent.Humanoid.Health > 0 then
print('touched')
wait(math.random(3,5))
local explosion = Instance.new("Explosion", workspace)
explosion.Position = script.Parent.Position
explosion.Parent = workspace
script.Parent:Destroy()
end
end))
1 answer
In programming especially Java we often wrap thing to obtain additional functionality when needed. The purpose of the debounce module it to apply a new debounce for the function that is passed.
To look at how this works we can break down the code into stages. Note this example is not using a module as it is easier to show in one script:-
local deb = false -- scope is outside the function
local function deb()
if deb then return end -- check and return out of code
deb = true
-- code
deb = false
end
The code above is the basic setup of a debounce. The down side is that this would require us to hard code each new deb variable. To resolve this we can wrap one function with this debounce variable which requiores a new function to be created. the call would be deb function -> passed function.
This can be show as:-
local function deb(func)
local deb = false -- the scope of this variable only exists within the returned function so each function passed has its own variable that is not shared.
-- wrap our passed function in a new function which only holds the debounce logic
return function()
if deb then return end
deb = true
-- run our function passed in deb
func()
deb = false
end
end
This would work in some cases but we still rewuire and arguments that are passed when the function is ran ie
local newFunction = deb(function(txt) print(txt) end)
newFunction('hi') -- this would not print as we have not passed any arguments.
To resolve this we use .. for a Variable Number of Arguments which is as simepe as passing the arguments from our new function to our passed function.
local function deb(func)
local deb = false
return function(...) -- all arguments
if deb then return end
deb = true
func(...) -- pass all arguments
deb = false
end
end
But what about a return value? In the wiki this code is designed to work for functions passed to events which do not require a return. This however can be added in.
local function deb(func)
local deb = false
return function(...)
if deb then return end
deb = true
local res = {func(...)}
-- we must set the debounce and not just return the functions result
deb = false
return unpack(res) -- unpack the table and pass back the arguments
end
end
This example above will also handle passed arguments e.g
local function deb(func)
local deb = false
return function(...)
if deb then return end
deb = true
local res = {func(...)}
deb = false
return unpack(res)
end
end
local tmpF = deb(function(a) return a, 'b' end)
local a, b = tmpF('a')
print(a,b) -- prints a and b
Some points on module scripts A module script is used to share the same code in multiple places. It is very common to have a deounce used so putting it in a module is the logical solution.
A module must return one value in most cases they return a table which holds all of the functions available.
As showm above this code is not dependant on a moudle script it is simply used as a means not to dublicate code.
I hope this helps. please comment if you do not understand how / why this code works.
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