Checking if a Module has a function?

Help and Feedback Scripting Support
1

Hi,
I’m looking to check if a ModuleScript has a function in it before proceeding; I’ve seen this method:

However, it doesn’t seem to work.

1 Like
2

You can use pcall() to achieve this. It takes a function, executes it and returns false if any errors happen in the function you passed to pcall(). For example:

local module = require(SomeModule)

if pcall(function()
    module:SomeMethod()
    -- NOTE: This function is actually executed so keep that in mind.
end) then
    -- Module has that function
else
   -- Module doesn't have that function
end
3

Modules are tables, so treat them as such.

If I had a module with a function named Test, I could try to index the module using “Test” as the key. If it returns nil, then the function doesn’t exist. If the function exists, the function will be returned.

I would write out the code for illustrative purposes, but I’m on mobile right now.

If you have any questions, let me know. I hope this helps.

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4

Modules are not tables, they are objects that return a value upon using a special function, require. A required ModuleScript will evaluate to what it returns. If you do not return a table, then you don’t have a table. Modules should not be treated as tables unless you are returning one.

5

That can be done without needing to call any function.

local module = require(TheModule)
local containsFunction = (type(module) == "table") and (type(module["FunctionName"]) == "function")
print(containsFunction)
14 Likes
6

What other applications are there for ModuleScripts beside returning a table of functions (and sometimes, variables)?

7

If the method you cited isn’t working, your module might be formatted awkwardly. Can we what you are returning?

8

Single-function returns, e.g. fastSpawn which returns a reusable function and not a table of functions or variables.

2 Likes
9

I sometimes use modules to implement custom classes.

return (function()
    local object = {}
    object.value1 = 38
    object.value2 = "hello"

    function object:getter1()
        return self.value1
    end
    function object:setter1(v)
        self.value1 = v
    end
    return object
end)

local constructor = require(module)
local object = constructor()
object:setter1("test")
print(object:getter1())
1 Like
10

this feels like your overdoing oop just to get a little more info on functions but to each there own I like to keep things more simplified.