From: kjana@...4lab.to (YANAGAWA Kazuhisa)
Date: 2002-09-24T12:43:04+09:00
Subject: Re: Problem with x.downto(y) {}

In message <ea5341b.0209231256.1dec46de@posting.google.com>
tokikenshi@anime-genesis.com writes:

> # snip
> @curLen.downto(1) do |i|
>   @snake[i].x = @snake[i - 1].x
>   @snake[i].y = @snake[i - 1].y
> end
> # snip
> 
> @curLen is an integer with the value 20 and @snake is an array
> containing structures for defining coordinates. The snippet above is a
> part in a snake-clone where the element 0 in array @snake is the head
> which is feeded with new values each cycle. This piece of code
> controls the flow of coordinates for each point of the snake.

I can't find problem too since the following works:

    arr = [1, 2, 3, 4, 5]
    arr.size.downto(1) {|i| arr[i] = arr[i-1]}
    arr[0] = 0
    p arr  #=> [0, 1, 2, 3, 4, 5]



> Every time I run this code Ruby dies with no message at all.
> Help, please!

So really wanting to fix the problem, more information is needed.
However this particular case, I can propose an alternative: Use
Array#unshift.

    arr = [1, 2, 3, 4, 5]
    arr.unshift(0)
    p arr  #=> [0, 1, 2, 3, 4, 5]

Urgh you don't want the last element, you can kill it by Array#pop.
Maybe overkilling and inefficient, but it works.


-- 
kjana@dm4lab.to                             September 24, 2002
Art is long, and time is fleeting.