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- Subject: Re: Globals (more ruminations)
- From: "Juri Munkki" <jm_list@...>
- Date: Thu, 15 Jul 2010 13:32:16 +0300
On Mon, July 12, 2010 2:56 pm, Roberto Ierusalimschy wrote:
> The default is no declaration. Only coders concerned about their use
> of globals (e.g., people writing modules or large programs, or people
> complaining about global-by-default ;) would add such thing.
>> Perhaps it should be an argument to the load*() function?
> Global declaration would be a purely syntactical thing. It does not
> improve "security" in any way; one can always write "_ENV.x" to
> access any global. It would only control the availability of a syntax
> sugar. So, I think it is the one writing the chunk that has a say about
> whether she wants or not the sugar, not the one using the chunk.
I think I like what Roberto Ierusalimschy is suggesting, assuming I'm
understanding it correctly. Here's how I see a "global" declaration
a = 10; -- a is a global (global assignment checking isn't
b = 20; -- b is a global too
global checks; -- using the global keyword turn global assignment
-- "checks" is a global, but it's just a dummy in this
case and not used.
global a, b; -- a and b are globals (same ones as above)
local c; -- nothing new here
a = b + 1; -- Without the declaration above, the assignment
would result in a
-- compile time error here.
c = a + b; -- This line would be OK even without the global
When you "require" a library, the loaded code chunk should revert to the
default (non-checked behavior) for backward compatibility.
Should function declarations (as above) be exempt or should I have written
global function hello()? I kind of like the idea of checking function
declarations as well.