initial release

cosmic rage/lua/declare.lua

@@ -0,0 +1,47 @@
+-- declare.lua
+-- See: http://www.gammon.com.au/forum/?id=7327
+--
+-- If you use this inside a function you cannot access global variables that have
+-- not already been declared, and must declare all local variables
+
+function force_declarations ()
+  setfenv (2, setmetatable ({}, 
+           {
+           __index = function (t, n) 
+                      error("variable '"..n.."' is not declared", 2) 
+                      end, 
+           __newindex = function (t, n, v) 
+                      error("assign to undeclared variable '"..n.."'", 2) 
+                      end })
+           )
+end -- force_declarations
+
+return force_declarations
+
+--[[
+
+  Example of use:
+  
+  
+  require "declare"
+  
+function test (x)
+  -- capture any global variables we want
+  local print = print
+  
+  -- after this we can't access global variables, and must declare local ones
+  force_declarations ()
+  
+  -- must declare every variable now before we use it
+  local a, b, c
+  
+  print (a)  
+  a = 1
+  b = 2
+  c = x * 2
+  print (c)
+end -- test
+
+test (1)
+
+--]]