Re: 5.2 feature list?

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

Biggest feature request on my radar is to sort out the automatic global 
variables issue which seems to me to be the only serious design flaw in 
Lua (and yes, I can see how it probably developed historically as Lua 
got progressively used for larger projects than originally intended). I 
know Roberto has code to work round this, but when I tried it it crashed 
Girder spectacularly! It is also expensive looking.

What I'm looking for is something like OPTION EXPLICIT available in some 
versions of Basic. This disables automatic global variables and forces 
you to declare them before use. In Lua, there'd be a switch you'd put at 
the start of each chunk and it would force you to use _G.name = value 
syntax to CREATE an entry in the global environment table (or in Lua 
cant, to set an entry to a value other than nil). You would still be 
able to access or reassign an existing global without the _G syntax.

I suggest that, under OPTION EXPLICIT you would also have to use _G to 
set a variable to nil to make it harder to accidentally delete someone 
else's global.

It would be good to also be able to set OPTION EXPLICIT as the default 
when creating a Lua interpreter in C.

I'm only using OPTION EXPLICIT as shorthand here as it is something 
people might be familiar with. In many ways, I'd prefer OPTION LOCAL and 
OPTION GLOBAL (or some other syntax for flagging directives). Here 
OPTION GLOBAL is what we've got now. OPTION LOCAL would behave as 
suggested above, but additionally it would allow dropping of explicit 
"local" specification of variables. Variables without a table specifier 
would be created local.

Would Roberto maybe admit that if he was redesigning Lua from scratch 
today variables would be local by default and global by declaration? If 
not, why not?

- John