From: Marnen Laibow-Koser <marnen@...>
Date: 2009-12-30T01:47:43+09:00
Subject: Re: Creating my own method for sorting an array

Robert Klemme wrote:
> 2009/12/29 Marnen Laibow-Koser <marnen@marnen.org>:
>> Joe User wrote:
> 
> Somehow I believe I heard that name somewhere already... :-)
> 
>> In Ruby, this is frankly stupid. �No Ruby programmer would do this in
>> any other way than by using the .sort method, providing a comparator
>> block, and letting Ruby take care of the bookkeeping.
> 
> I don't see how that is a stupid exercise.  I reckon this is not
> mainly an exercise to introduce sorting but rather to get accustomed
> with class Array and probably algorithms in general.

Then they probably should have picked a better example, or at least 
explained common sort algorithms before turning you loose v

> 
>>> and compare it to the rest of the elements and if it's the smallest,
>>> push it onto the sorted list and push the remaining elements onto the
>>> unsorted. �Then call the method again with the sorted and unsorted
>>> lists. That's the recursion part.
>>
>> That would certainly be a way of doing it. �Have you written automated
>> tests to encapsulate these requirements? �If not, do so before writing
>> another line of code.
> 
> Maybe it's a bit early to start writing tests when someone is starting
> to learn to program...

No.  Testing is a fundamental part of programming, though it is often 
neglected.

>  When I started learning software development I
> certainly got more kick out of a working program than a working unit
> test before hand. :-)

It's the working test beforehand that lets you know when you have a 
working program.  It really is best to write the tests first.  Read up 
on test-first development and apply it religiously -- it really is worth 
it.

> 
>>> I guess the problem I'm having is knowing how to check each element of
>>> the unsorted array against the other elements. �I can check if the
>>> current element is smaller than the other elements using < (less than)
>>> but that doesn't mean it's the smallest in the whole array.
>>
>> Sure it does. �(Of course, this is quite computationally inefficient.)
> 
> As I said, I don't believe this is the point of the exercise.
> 

Perhaps not.  And it may be a good exercise for learning algorithmic 
concepts.  But really, it teaches you nothing good about writing 
idiomatic, efficient Ruby.

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen@marnen.org
-- 
Posted via http://www.ruby-forum.com/.