Re: CHanging the order of parameters, is that possible?

[Rena <hyperhacker@...>]

On Sat, Jan 5, 2013 at 2:00 PM, Choonster TheMage
<choonster.2010@gmail.com> wrote:
> On Sun, Jan 6, 2013 at 3:35 AM, Rena <hyperhacker@gmail.com> wrote:
>>
>> On Sat, Jan 5, 2013 at 11:07 AM, Marc Balmer <marc@msys.ch> wrote:
>> > Is it possible to change the order of parameters in a function taking
>> > varargs?  Maybe using the select(n, ...) function?
>> >
>> > This is what I want to do:
>> >
>> > function foo(fmt, ...)
>> >     -- switch element 1 and 2 of {...}
>> >
>> >    print(string.format('%d %s', ...))
>> > end
>> >
>> >
>> > foo('%s %d', 42, 'balmer')
>> >
>> > (background is doing i18n in Lua, whith messages (= format strings) that
>> > can have the order of parameters changed)
>> >
>> >
>>
>> You can probably hack up something to rearrange parameters, but a much
>> better idea for i18n is string.gsub:
>>
>> function foo(fmt, ...)
>>         local values = {...}
>>         print(('$2 $1'):gsub('%$(%d+)', values))
>> end
>>
>> That doesn't handle format strings, but you could easily extend it to
>> a syntax like $(1.6f 3) to mean the third key formatted with %1.6f.
>>
>> --
>> Sent from my Game Boy.
>>
>
> If you were willing and able to modify the string library's source (or
> copy/paste the string.format definition and possibly its helper functions
> into a new file), you could add back parameter indexes to string.format
> patterns; which was apparently present in Lua 4.0. The author of lua-wow (a
> Lua distribution slightly modified to match World of Warcraft's embedded
> Lua) did it here:
> https://github.com/luaforge/lua-wow/blob/master/trunk/src/lstrlib.c#L771-L776
>
> This uses the same syntax as the GNU formatted output described here:
> http://www.gnu.org/software/libc/manual/html_node/Output-Conversion-Syntax.html#Output-Conversion-Syntax
>
> So you can use this as foo:
>
> function foo(fmt, ...)
> print( ("%2$d %1$s"):format(...) )
> end
>
> But you may not want to mess around with the source or define a separate and
> slightly modified version of string.format.

Hmm, that was in 4.0? I wonder why it was removed...

-- 
Sent from my Game Boy.