From: Sharon Phillips <phillipsds@...>
Date: 2007-11-30T21:17:02+09:00
Subject: Re: Delete array element within iterator block?


On 30/11/2007, at 10:51 PM, Jari Williamsson wrote:

> How do I (in an elegant way) delete an element of an array within a  
> block, while using a block iterator?
I assume using delete_if is no good in this situation?
[1,2,3,4,5,6].delete_if{|i| i>4}
 > [1,2,3,4]

>
>
> The code below won't work (the wanted behavior here is to get all  
> array elements to print and but also delete the 2nd element after it  
> has been encountered):
> ---
> arr = [1,2,3,4]
> arr.each_with_index { |e, i|
>  p e
>  arr.delete_at(i) if i == 1
> }
> ---
> results in:
> 1
> 2
> 4
This is interesting, because although the results printed on the  
screen imply the 3 was removed, if you look at the array afterthe  
operation you'll see it was the 2 removed (as we wanted)

irb(main):013:0> (a=[1,2,3,4]).each_with_index{|e,i| p  
e;a.delete_at(i) if i==1}
1
2
4
=> [1, 3, 4]

I've no ideas why

Cheers,
Dave

>
>
> Of curse, I could loop and keep track of the index manually, but I'm  
> mainly checking if there is any built-in stuff here.
>
>
> Best regards,
>
> Jari Williamsson
>