Asking a variable its name

[Jose Torre-Bueno <jtorrebueno@...>]

For debugging outputs I have occasionally wanted to ask a variable its name.  I don't know a direct way to do this but I notice that the type of the values given to __index are a table and a string.
Following that lead I discovered that the following will give me a variable's name as a string

> tricktable = {__index = function (_,v) return v end}
> setmetatable(tricktable, tricktable)
> a = 1
> =a
1
> =tricktable.a
a
> =type(tricktable.a)
string

This seems a roundabout way to get something and of course I can't make this into a function because all functions are call by value.  I came up with this experimenting with rawget which actually needs a string as its second parameter.  I was led to this because strict.lua traps access to undeclared globals.  That is nice but it prevents the construction: 

local something = a_global_if_it_exists or the_default_value  

because strict will trap a_global_if_it_exists instead of letting it be nil.  I thought to make a function that would use strict's declared table to return the value of a variable if it existed or nil for those cases where I want explicitly to test if a variable is declared without causing an error but I don't see how this could be made into a function.  A macro would work if Lua had macros.

Is there some much more straightforward way of doing this that I am missing?


Jose de la Torre-Bueno, Ph.D.
Empowered Energy Solutions Inc.
Intellectual Property & Technology Management
T (619) 977-0553
F (760) 295-7119
jtorrebueno@cox.net