Re: Default value in function parameters?

[Rici Lake <lua@...>]

On 20-Sep-06, at 3:55 AM, Philippe Lhoste wrote:
> > But more Lua like would be:
> > a = { a = 1,
> >       b = { b = 2,
> >             c = {native = 1, rock = 2}[style] or 0
> >           }
> >     }
>
> Argh! WOULD BE! I tried it, and wondered by I had syntax errors...
> Indeed, it seems a bit strange at first, but it is quite elegant in 
> its simplicity (and no new keyword...).

This is the version which works with current Lua (5.1.1):

> style="native"
> a = { a = 1,
      b = { b = 2,
            c = ({native = 1, rock = 2})[style] or 0
          }
    }
> =a.b.c
1

The parentheses are necessary because of an obscure syntactic issue, 
although it doesn't apply in that particular context. It's the same 
reason you need to use:

  ("%d"):rep(#t):format(unpack(t))

instead of the possibly more natural

   "%d":rep(#t):format(unpack(t))

(The former was the answer to a question on IRC the other day: how do I 
turn a
table which looks like {1, 2, 0, 9, 7, 5} into the string "120975".)

R.