How to call a function whose name is in a string variable?

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#1 
local FuncToCall

function Func1()
    print("Hello1")
end

function Func2()
    print("Hello2")
end

FuncToCall = "Func1" 
FuncToCall = "Func2"

How to call “Func1” or “Func2” using the string stored in the variable “FuncToCall”?

#2

There are a few ways to do this, but I’d suggest treating the functions as variables and storing them in a table.

local FuncToCall

local funcs = {}
function funcs.Func1()
    print("Hello1")
end

function funcs.Func2()
    print("Hello2")
end

FuncToCall = "Func1" 
FuncToCall = "Func2" 


local func = funcs[FuncToCall]
if func then
    func()
end
5 Likes
#3

Use getfenv()

getfenv()['Func1']()
1 Like
#4

yeahhhhhhhhh… don’t do that. Using getfenv() disables some of Luau’s optimizations and isn’t good practice to begin with.

1 Like
#5

Be more specific then, I’m interested what specifically is the issue with that. Because that answers his direct question without suggesting alternative.

#6

You don’t use it for the same reason you don’t use _G, and, by doing that you have essentially “tainted” the environment. When you do table.insert you can’t guarantee you are getting the right thing anymore, and like i mentioned it deoptimizes the env.

The use of any of these functions performs a dynamic deoptimization, marking the affected environment as “impure”. The optimizations are only in effect on functions with “pure” environments - because of this, the use of loadstring / getfenv / setfenv is not recommended. Note that getfenv deoptimizes the environment even if it’s only used to read values from the environment.

source
1 Like
#7

Why?
In the same source:

When appending elements to tables, it’s recommended to use table.insert

#8

No, that was an example. I see your confusion lol. I am saying you can’t guarantee that in that example table even refers to the built-in library anymore once the env is tainted.

1 Like
#9

setfenv and getfenv are some old black magic with lua and are designed to do specifically what this post is asking about, but are not exactly advised.

3 Likes