Re: Lua 5.2 wish item: Splicing

[Tuomo Valkonen <tuomov@...>]

On 2006-11-09, Javier Guerra <javier@guerrag.com> wrote:
> Mark Hamburg wrote:
>>     column{
>>         spacing = 10,
>>         $makeChildren(),
>>         view{
>>             title = "footer",
>>         }
>>     }
>> 
>> Where the $ means that we take all of the results from the function rather
>> than just the first. 
>
> i'd prefer to have it the other way around, that is using all values by 
> default.

I'd actually prefer it never using all the values by default, as it
currently sometimes (but not always) does.

How about extending the ... syntax?

    foo { bar = 1, ... = fn(), baz = 2 }

And 

    a... = fn()

for

    a = { ... = fn() }


Or perhaps also

    foo { bar = 1, fn() ..., baz = 2 }

(although postfix "operators" may not be such a good idea).


You could then also allow for naming the "vararg" structure
with a similar syntax:

    function foo(bar, opts...)

         for k, v in ipairs(opts) do whatever end

    end

Likewise you could call a function, expanding a table. You could
even support non-integer fields going into the vararg structure as
named parameters (although that may not be so simple with ... no
longer being a table):

    function foo(bar, opts...)

        if opts.quk then whatever end

    end

    foo({1,2,3, quk = true}...)

	=> bar = 1, opts={2,3,quk=true}

Or maybe, to simplify things, an expanded table should always be
the vararg table, and maybe there could be just one of them in
a function call.

-- 
Tuomo