lua newproxy用途

What does newproxy() in 5.1?

> I find newproxy a curious addition.  It gives you unique userdata that
> share the same metatable.  I cannot think of a use for it yet.
> What did you have in mind?

This is a very experimental feature. We wanted a simple and secure way
of creating userdata in Lua. It has several uses, such as to monitor
garbage collection, as a light "unique" object, and for testing ;-).
But we cannot allow Lua to change the metatable of those userdata;
otherwise, Lua could break other libraries (e.g. give one of these
userdata as a file to be closed). To allow each userdata to have its own
new metatable or to share the metatable of another such userdata seems
flexible and secure.

userdata to be collected still counts into new GC threshold, increasing memory consumption.
Reported by Roberto on 25 Jul 2003. Fixed in 5.0.2.

这是用法：
Example:

a = newproxy(true)
getmetatable(a).__gc = function () end
for i=1,10000000 do
  newproxy(a)
  if math.mod(i, 10000) == 0 then print(gcinfo()) end
end


搞了半天原来主要是用来产生大量的具有相同的行为的小对象 主要是做测试用的。

萝卜神也搞得太忽悠人了。