Re: Lua voices

[Sean Conner <sean@...>]

It was thus said that the Great Laurent FAILLIE once stated:
> Hi,
> I would like to see in Lua :

> 1/ As I discussed several times : Thread safe State sharing. For the
> moment, or you have to "send" bytecode among threads or use a lock
> mechanism which seem to penalize by a large amount performances. I would
> like to have an option at compile time enabling thread safe Lua, having
> out of the box transparent semaphore locking on global objects. Something
> efficient, easy :)

  You can recompile Lua with lua_lock() and lua_unlock() defined, but then
you get Python performance because of the "global interpeter lock" you just
introduced.

  Second, locking "global objects" isn't enough:

	do	-- new local scope
	  local data = {}
	  spawn_thread(foo,data) -- one system thread using data
	  spawn_thread(bar,data) -- a second system thread using data
	end

  You really need the fine grained locking that lua_lock() and lua_unlock()
provide.

  Easiest answer---just say to no system threads 8-P

> 2/ yes, I'm missing compactness of C compoundeds operator like += *= :?
> and so on ... something suggested it seems several times on this list but
> seems always disdained by gurus.

  Question to answer:  is

	x += b

the same as

	x = x + b

at the metatable level?  That is, will (assuming at least one object has a
metatable with the __add() function defined):

	x += b

do

	mt = getmetatable(x) or getmetatable(b)
	x = mt.__add(x,b)

or is this a "different" operator?  I only ask becuase Python has

	__add__()	x = x + b
	__iadd__()	x += b

  But I think the reason that Lua doesn't support this is that it
complicates the grammer or parser.

  -spc