On Mon, Jun 21, 2021 at 1:48 PM Soni "They/Them" L. wrote:
local _GETNAME = function(o, k)
if type(o) == "table" and k == "insert" then return table.insert end
return o[k]
end
This allows doing t:insert(foo) on any table t.
Found one more example:
I want to replace the standard string method
s:gsub(pattern, repl [, n])
with my customized variant
s:gsub(pattern, repl [, n] [, plain])
So, I redefine string.gsub
But it does not have any effect under a sandbox because strings' metatable is global, I have just my private copy of _ENV.string.
Indeed, if we can redefine accessing global variables locally in runtime (due to _ENV), why not having the same feature for other actions?
I'd like to have two special optional fields inside _ENV table: _NEWTABLE and _INDEX
_NEWTABLE would keep a function invoked automatically as the final step of creating a table from a table constructor.
For example, the statement
x = {1, 2, 3}
would silently act like
x = _ENV._NEWTABLE{1, 2, 3}
"__index" metamethods for "type-shared metatables" are better to make local (per chunk) instead of global (per VM) and make accessible without the debug library.
"Type-shared metatables" are: the metatables for strings/numbers/functions, and highly requested shared metatable for all metatable-less tables.
_ENV._INDEX would keep local versions of "__index" metamethod for "type-shared metatables".
For example, local redefinition of gsub would look like
_ENV._INDEX.string = setmetatable({gsub = mygsub}, {__index = _ENV._INDEX.string})
And this is how Soni can use t:insert() for any table inside his module:
_ENV._INDEX.table = _ENV.table
