RE: Implicit Globals - A compile time solution.

["John Hind" <john.hind@...>]

David,

You seem to be reading more into the suggestion than was intended - all I 
suggested was a change in *default* behaviour which by definition only alters 
syntax. Locals still work exactly as before, just you do not need the "local" 
keyword (unless you want to restrict the scope of a local further). Globals 
still work as before, just if you want to assign to one you need to use table 
syntax (or there could be a global keyword as sugar for this). You can still 
*access* a global without table syntax, so "print" is still global because its 
library would have explicitly inserted it in the global table.

In your example, "n" would now be a local at the outer lexical scope, so all 
the inner references would see it and would therefore *not* create new, more 
local, variables. If you *wanted* to create a more local "n" you'd still have 
to use the local keyword. "global" still refers to the global environment 
table - you can be "more local" but you cannot be "more global", you can only 
be "global".

As for the "foo" variable referencing the function, I agree that would need 
some thought. In the pure form, that would become an outer scope local as well 
and you'd have to use "_G.foo" if you wanted it to be global. However the 
existing syntax sugar gives a convenient and natural exception mechanism for 
functions if we want. The sugar form of function creation, as your example, 
could still be global-by-default while the native form would be 
local-by-default in line with all other variable assignments.

The suggestion does not alter the language in any fundamental way, just the 
"path of least resistance" for naive (or in my case, careless!) programmers.

- John

-----Original Message-----
From: David Given [mailto:dg@cowlark.com]
Sent: 20 February 2008 15:56
To: Lua list
Subject: Re: Implicit Globals - A compile time solution.

Examine the following code:

n = 1
function foo()
  return function()
    return function()
      if bingy then
        print(n)
      end
      print(n + 1)
    end
  end
end

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