Re: Variable number of arguments functions - arg not declared

[Patrick Donnelly <batrick () batbytes com>]

On Mon, May 28, 2012 at 12:49 PM, Aleksandar Nikolic
<nikolic.alek () gmail com> wrote:
> Hi all,
>
>
> I've merged the changes from trunk to my exp branch
> to change the scripts I'm working on to suit new lua updates.
>
> I've had a problem with variable number of arguments functions
> in rmi.lua library.
>
> As far as I can tell, "arg" variable is deprecated in new version.
>
> For example:
>
> local function dbg(str,...)
>        stdnse.print_debug(3,"RMI:"..str, table.unpack(arg))
> end
>
> Would throw an error saying arg was not declared.
> I changed that to:
>
> local function dbg(str,...)
>        local arg={...}
>        stdnse.print_debug(3,"RMI:"..str, table.unpack(arg))
> end
>
> Am I doing something wrong?
> I'm bringing this to your attention as it might not be the only place
> arg is used.

arg was a feature of Lua 5.0. Lua 5.1 provided compatibility support
for it which was removed in 5.2.

When dealing with varargs, you usually use these Lua functions:

http://www.lua.org/manual/5.2/manual.html#pdf-table.pack
http://www.lua.org/manual/5.2/manual.html#pdf-table.unpack
http://www.lua.org/manual/5.2/manual.html#pdf-select

Keep in mind you can treat the vararg as a regular expression (list).
In particular, this code:

> local function dbg(str,...)
>        local arg={...}
>        stdnse.print_debug(3,"RMI:"..str, table.unpack(arg))
> end

can be simplified as

> local function dbg(str,...)
>        stdnse.print_debug(3,"RMI:"..str, ...)
> end

This subject is talked about in the manual [1] but it is very terse.
If you have questions on this, feel free to email me about it.

[1] http://www.lua.org/manual/5.2/manual.html#3.4.10
-- 
- Patrick Donnelly
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