debug.getstack

Gets one value or all values from a Luau stack frame.

Syntax

debug.getstack(level: number, index?: number) -> any | {any}
debug.getstack(thread: thread, level: number, index?: number) -> any | {any}

Parameters

Parameter	Type	Description
`level`	`number`	The stack level (1 = current function)
`index`	`number?`	The stack slot index. Omit it to return every value at the level
`thread`	`thread?`	Optional thread to inspect before `level`

Returns

Type	Description
`any` or `{any}`	The selected value, or an array of every value when `index` is omitted

Description

debug.getstack retrieves values from a Luau call frame. It throws if level refers to a C closure, including level 0.

Example

local marker = "caller value"

local function inspectCaller()
    local callerStack = debug.getstack(2)

    for index, value in ipairs(callerStack) do
        print(index, value)
        assert(debug.getstack(2, index) == value)
    end
end

inspectCaller()

Stack Levels

Level	Meaning
1	Current function
2	Calling function
3	Caller of the caller
...	And so on

Notes

Stack indices correspond to local variable slots
The exact index depends on the function's compiled bytecode
Values can include locals, parameters, functions, and temporary stack slots
Stack layout is compiler-dependent; do not assume an index without inspecting the frame

debug.setstack - Modify a stack value

debug.getstack

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