debug.getupvalue

Returns the upvalue at the specified index. An error should occur if the index is invalid.

function debug.getupvalue(func: (...any) -> (...any) | number, index: number): any

Parameters

• func - The Lua function/level the upvalue would be obtained from.

• index - The position of the wanted upvalue.

---

Examples

local UpFunction = function() print("Hello from up") end

local function DummyFunction()
    UpFunction()
end

local Upvalue = debug.getupvalue(DummyFunction, 1)
Upvalue() -- Output: Hello from up

local function DummyFunction() end

debug.getupvalue(DummyFunction, 0) -- Should error due to invalid index passage

debug.getupvalue(print, 1) -- Should error due to invalid index and C closure passage