Re: ... as an "expand list" unary postfix operator

[Doug Currie <doug.currie@...>]

On Aug 14, 2009, at 12:00 AM, David Manura wrote:

> One of the prototypical problems in [1] was to implement a function  
> this:
>
>  --Wraps a function with trace statements.
>  function trace(f)
>    return function(...)
>      print("begin", f)
>      local result = tuple(f(...))
>      print("end", f)
>      return result()
>    end
>  end
>
> Could we add new keywords that correspond with the TUPLE/DETUPLE
> opcodes to achieve something like the above?
>
> [1] http://lua-users.org/wiki/VarargTheSecondClassCitizen


Would this work?

function trace (f)
  return function(...)
    print("begin", f)
    local function vals(...)
      print("end", f)
      return(...)
    end
    vals(f(...)...)
  end
end

e