Re: self copying functions

[Sam Roberts <sroberts@...>]

On Fri, Mar 16, 2007 at 07:22:56AM +0900, Miles Bader wrote:
> Graham Wakefield <lists@grahamwakefield.net> writes:
> > Except that I can't figure out how to make a copy of a function in  Lua
> > (or in the Lua API).  I guess I need to create a new closure,  which I
> > can do with a cfuntion, but I can't see how to do it with a  lua
> > function.

Graham:

What about a function do you want to copy?

Functions have state ("closures"/upvalues) that can't be stripped from
them so easily:

  function n()
    local i
	i = i + 1
	return i
  end

  print(n())
  print(n())

  n_copy = n


After you "copy" the function n, what would the relationship be between
n and the copy?

>    function copy_fun (fun)
>      return function(...) return fun(...) end
>    end
> [The extra level of indirection is ever so slightly annoying, but ...]

Miles:

Why would you prefer:

   load_copy = copy_fun(load)

to

   load_copy = load

?

Sam