[Help] Getting a return value from lua

[Beanzilla]

I have a lua script like below:

return {
    answer = 42,
    ok = true
}

I'd like to retrieve the table that the script has returned, I've seen the other issue #101, and I don't quite understand how to obtain the return value.

Perhaps I need an example of how to access it.

Just a short example will do, as once I see it I am sure I'll be able to work my way to understanding how to do it for further cases.

[TimVosch]

After performing DoString (or DoFile) the result will be at top of the stack.
Since you return a table you can fetch the items using L.GetField

Example:

func TestReturnDoString(t *testing.T) {
	L := lua.NewState()
	L.DoString(`return { answer = 42 }`)
	assert.True(t, L.IsTable(-1)) // Should be true!
	L.GetField(-1, "answer")
	assert.Equal(t, 42, L.ToInteger(-1))
}

Note that LoadString (or LoadFile) does not actually execute the file, but rather returns a function that contains the file. In that case you need to L.Call the loaded chunk first.

func TestReturnTableFromLoadString(t *testing.T) {
	L := lua.NewState()
	L.LoadString(`return { answer = 42 }`)
	assert.True(t, L.IsFunction(-1)) // Should be true!
	L.Call(0, 1)                     // Has 0 parameters, and returns 1 value
	// Returned value will now be at the top of the stack
	assert.True(t, L.IsTable(-1)) // Should be true!
	L.GetField(-1, "answer")
	assert.Equal(t, 42, L.ToInteger(-1))
}

To know what functions do with the stack, refer to the Lua Manual.