Re: _SELF and _SUPER

[Sean Conner <sean@...>]

It was thus said that the Great Soni L. once stated:
> 
> _SELF and _SUPER would make the compiler insert some things into the 
> bytecode that don't get erased/don't count as "debug info".
> 
> Using debug.* is literally relying on debug info. And order of 
> locals/upvalues. And so on. None of that is guaranteed, while the 
> proposal can use mechanisms not yet available and stuff.
> 
> For example, this code:
> 
> local x;
> print(_SELF["x"])
> 
> Could produce a sequence of opcodes like:
> 
> R(1) = nil -- e.g. LOADNIL
> R(2) = Upval[1][K(1)] -- e.g. GETTABUP
> R(3) = K(2)[K(3)] -- e.g. GETTABLEK / GETTABLE with a statically 
> allocated table constant
> R(3) = R(R(3)) -- e.g. MOVEI / move from indirect register (because the 
> I is on the right, and the RHS is the source)
> R(2)(R(3)) -- e.g. CALL
> 
> where:
> 
> K(1) = "print"
> K(2) = statically allocated table: {["x"] = 1}
> K(3) = "x"
> 
> This would be for reading only. For writing, it'd use R(R(x)) = R(y) 
> (e.g. IMOVE) instead. For calling, it'd retrieve the current function 
> from the call stack or something. For passing it around, it'd copy all 
> locals into a table, maybe set a __call metamethod as well.

  To what end?  What problem does this solve?  What you one use this for?

  -spc