Re: default LUA_TTABLE metatable, like for strings

["temp 213 qwe" <temp213@...>]

On Sun, 17 Mar 2019 22:40:34 +0200
 Dirk Laurie <dirk.laurie@gmail.com> wrote:
> Op So. 17 Mrt. 2019 om 18:25 het temp 213 qwe 
> <temp213@gorodok.net> geskryf:
> > On Sun, 17 Mar 2019 12:42:32 -0300
> >   Luiz Henrique de Figueiredo <lhf@tecgraf.puc-rio.br> 
> > wrote:
> > > What problem does this proposal solve?
> >
> > Absence of default metatables.
> Since 'table' is Lua's only data structure, which does duty for
> arrays, sets, dictionaries, lists, queues, stacks, XML encodings,
> matrices etc, it would be quite annoying to find every table one
> creates pre-equipped with a metatable that serves only one of these.

It affects only the tables WITHOUT a metatable, as soon as you 
setmetatable(), table would use it instead.
If arrays, sets, dictionaries, lists, queues, stacks, XML 
encodings, matrices, etc do not set/change own metatable, it 
means that it do not use any metamethods either, except 
__index/__newindex.
But yes, theoreticaly you could break the normal operation of 
other things by redefining __index, __newindex metamethods by 
default to something strange.
And there is no need to set G(L)->mt[LUA_TTABLE] to {__index = 
table}, like it is done for the strings with {__index = string 
library}, G(L)->mt[LUA_TTABLE] could also be NULL by default, 
but see no disadvantage here, why not to make it for tables, 
if it was done like this for strings.