Re: _SELF and _SUPER
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- Subject: Re: _SELF and _SUPER
- From: "Soni L." <fakedme@...>
- Date: Sat, 6 Aug 2016 00:02:15 -0300
On 05/08/16 11:44 PM, Sean Conner wrote:
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
-- Example 1
print((function(x, y) return x == 0 and (y or 1) or _SELF(x-1, x*(y or
1)) end)(3)) --> 6
-- Example 2
local function a()
end
local function b()
end
local function c()
end
return function(x)
for i, opcode in ipairs(x) do
local op, arg1, arg2, arg3 = table.unpack(opcode)
_SUPER[op](arg1, arg2, arg3)
end
end
Etc. _SELF is more useful than _SUPER, all things considered.
--
Disclaimer: these emails may be made public at any given time, with or without reason. If you don't agree with this, DO NOT REPLY.
- References:
- _SELF and _SUPER, Soni L.
- Re: _SELF and _SUPER, Luiz Henrique de Figueiredo
- Re: _SELF and _SUPER, Soni L.
- Re: _SELF and _SUPER, Thomas Jericke
- Re: _SELF and _SUPER, steve donovan
- Re: _SELF and _SUPER, Rain Gloom
- Re: _SELF and _SUPER, Soni L.
- Re: _SELF and _SUPER, Sean Conner
- Re: _SELF and _SUPER, Soni L.
- Re: _SELF and _SUPER, Sean Conner