From: Mark Woodward <markonlinux@...>
Date: 2007-01-29T19:25:05+09:00
Subject: Re: Flow of execution

Hi Alex,

On Mon, 29 Jan 2007 19:09:35 +0900, Alex Young wrote:

> Mark Woodward wrote:
>> Hi all,
>> 
>> Could someone explain the 'flow' of how the eg below is processed?
>> My limited understanding is that the left hand side is the receiver and
>> the right hand side the method being passed to the receiver?
>> 
>> What I don't understand is where the block comes into the equation for
>> something like the following:
>> 
>> values = anagrams.values.sort do |a, b|
>>   b.length <=> a.length
>> end
>> 
>> 
>> The block changes how the sort method sorts? ie it sorts by length rather
>> than alphabetically? So it overrides the default meaning of <=>??
>> 
>> We get the values of the anagram hash by the 'values' method? 
>> We then do:
>> 
>> .sort do |a, b| b.length <=> a.length end
>> 
>> ie this whole line acts on the values array??
>> not a 2 step process of 1. the sort method then 2. the block applied in
>> some way?
>> 
>> To illustrate what I'm failing dismally to explain here:
>> Using () for grouping, is it processed as A or B?
>> 
>> A
>> values = anagrams.values.(sort do |a, b|  b.length <=> a.length)
>> end
> This, almost.  It's more like:
> 
> values = anagrams.values.sort(do |a,b| b.length <=> a.length end)
> 
> The block essentially acts as a parameter to the sort method.  The sort 
> method uses the result of passing each pair to the block to perform the 
> actual sorting.


excellent, thanks.

-- 
Mark