Re: Automatic Variables Local rather than Global (Proposal)

[Niklas Frykholm <niklas@...>]

John Hind wrote:
> As a long-time user of Lua in an environment where multiple scripters 
> share a common global table (Girder 4), there is just one thing in Lua 
> I'd really like to see changed. This is the automatic creation of 
> variables in the global environment table.
I'm torn on this issue. I think forcing declaration of local variables 
with "local" is good since it makes the scope of variables clear 
(especially important when you work with closures), but it is too easy 
to forget to write "local".

Having a "global" keyword would fix that, but having to declare all 
global functions "global" would be a slight bother (not too bad, 
though), and I wouldn't want to have different rules for functions and 
other things.

Currently, I do the following to spot missing "local"s:

---

function lock_new_index(t, k, v)
   error("module has been locked -- " .. k .. " must be declared local", 2)
end

function lock(t)
   local mt = getmetatable(t) or {}
   mt.__newindex = lock_new_index
   setmetatable(t, mt)
end
   
function f(y)
   x = y * y
   print(x)
end
   
function main()
   f(3)
end

lock(_G)
main()

// Niklas