Comparisons for what is "var2 = (var1 = value)" in other languages.

assign-operator.lua

function set_field(t, f, v)
	t[f] = v
	return v
end
local n = 10000000
local t = { }
local q
local p
-- Direct:
q = os.clock()
for i = 1, n do
	t.one = i
	t.two = t.one
end
print(os.clock() - q)
-- set_field:
q = os.clock()
for i = 1, n do
	t.two = set_field(t, 'one', i)
end
print(os.clock() - q)
-- inline function:
q = os.clock()
for i = 1, n do
	t.two = (function() p = i; return p end)()
end
print(os.clock() - q)