Do/end - What Is It & What Is It Used For?

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1

You may have come across a block of code with do/end and wondered what it was, as it’s not a common thing to see.

Simply put, do/end functions are for executing code in its own scope. For example, you would normally do this:

local a = 10
local b = 20
print(a + b) -- 30

--// Later in the code

local b2 = 25
print(b) -- prints 20 without error (b is a typo, as I meant to type b2)

With do/end, I do not have to worry about accidentally making a typo and using b.

do
    local a = 10
    local b = 20
    print(a + b) -- 30
end -- a & b die here

--// Later in the code

local b2 = 25
print(b) -- errors, since 'b' no longer exists

You can also use do/end to replicate a single-use function. You may see a lot of this in scripts:

--// CODE HERE

function begin()
    --// begin function's code here
end

begin()

You can replace that with:

do
    --// begin function's code here
end

In conclusion, do/end may not be a super common practice but it is certainly very helpful. I hope you learned something new!

7 Likes
2

I kinda wonder what’s an example of use case? This tutorial seems interesting.

3

An example could be the following:

-- Local Script

local setCore do
   local CoreGui = game:GetService("CoreGui")

   local MaxRetries = 8
   
   local function setCore(parameterName)
      local results

      for i = 1,MaxRetries do
         local success, result = pcall(CoreGui:SetCore)(parameterName, ...)
         if success then results = result end
      end

      return results
   end
end

setCore("ChatMakeSystemMessage", {
   Text = "Hi :)"
   Color = Color3.fromRGB(255, 255, 243),
   Font = Enum.Font.SourceSansBold
   TextSize = 18
})

setCore("SendNotification", {
   Title = "Welcome!",
   Text = "You are the 1st visitor!"
   Duration = 5
   --Icon = ""
   --Callback = workspace.BindableFunction -- path to BindableFunction
   --Button1 = "Yes"
   --Button2 = "No"
})

setCore("BadgeNotificationsActive", false)

setCore("PointsNotificationsActive", false)

Basically I am expect that you would not use CoreGui and MaxRetries again, but I expect you do use setCore() so I will put this in the open

1 Like
4

This won’t actually work since you define setCore locally inside of the do end block. You should remove the local keyword from the function definition:

local setCore do
    ...
    function setCore(...)
        ...
    end
end
1 Like