From: Jason Nordwick <jason@...>
Date: 2006-09-16T00:15:05+09:00
Subject: Re: arbitrary indexes

given that Array[int,int] is already taken syntax, Array[Array] is perfectly acceptable syntax for arbitrary list indexing, even if the immediate form might look a little ugly: a[[1,3,4,5,7]].

-j

MonkeeSage wrote:
> Farrel Lifson wrote:
>> Be careful though as you've broken some functionality as Array#[] can
>> take two arguments to return the y elements starting at index x.
>>  [1,2,3,4,5,6,7][2,3] = [3,4,5]
>> Your modification would make
>>  [1,2,3,4,5,6,7][2,3] = [3,4]
> 
> Yup, caveat emptor. Jason indicated that he was aware of the default
> functionality though, so I assume he would be mindful of that gotcha.
> 
> Also, I see that my code above wouldn't work for one of his desired
> uses:
> 
> a=[0,11,22,33,44,55]
> b=[1,3]
> a[b] # => [11, 33]
> 
> For that to be supported as well, the implementation would have to be
> something like:
> 
> class Array
>   def [](*args)
>     if args.size == 1
>       if args.at(0).instance_of?(Array)
>         values_at(*args.at(0))
>       else
>         at(*args)
>       end
>     else
>       values_at(*args)
>     end
>   end
> end
> 
> Regards,
> Jordan
> 
>