From: Marshall Farrier <info@...>
Date: 2011-07-25T01:25:04+09:00
Subject: Re: best style for setting items in a collection

Josh Cheek wrote in post #1012707:
> On Sat, Jul 23, 2011 at 8:41 PM, Marshall Farrier
> <info@marshallfarrier.com>wrote:
>
>>   arr[i] += arr[i - 1]
>> version is pretty short and sweet.
>>
>> --
>> Posted via http://www.ruby-forum.com/.
>>
>>
> It's hard to know how to answer this because you're overwriting the
> values
> of indexes that you use in calculations later on. This seems like it is
> probably unintentional: If arr was [1,1,1], then are you expecting
> [1,2,2]
> -- the value at index 2 is calculated based on the original value at
> index
> 1. Or are you expecting [1,2,3] -- the value at index 2 is calculated
> based
> on the new value at index 1?
>
> If the former, then this is equivalent:
> arr.each_cons(2).with_index(1) do |(left, right), index|
>   arr[index] = left + right
> end
>
>
> If the latter, then this is equivalent:
> (1...arr.length).each { |index| arr[index] += arr[index-1] }
Ok, sorry that my example muddled things so much. I did mean the latter. 
The point of departure is that arr initially holds the (non-leap-year) 
number of days in each month with 0 up front for month 0: [0, 31, 28, 
31, 30, 31, 30, 31, 31, 30, 31, 30, 31]. Then I want to modify it so 
that it holds the aggregate days in normal years up to the end of the 
month in question. I then use this array for various date calculations.

-- 
Posted via http://www.ruby-forum.com/.