From: dblack@...
Date: 2006-01-02T22:36:42+09:00
Subject: Re: About blocks

Hi --

On Mon, 2 Jan 2006, Robert Klemme wrote:

> Surgeon <biyokuantum@gmail.com> wrote:
>> Hi,
>> 
>> (This question might be answered previously. If so, I apologize.)
>> 
>> Can we *ALWAYS* use plain methods instead of blocks? Yes, sometimes
>> using a block may be obviously better than using a method but I mean,
>> are there any situations in which the *ONLY* solution is to use a
>> block rather than a method? May someone be forced to use only and
>> only a block? I ask this because I am not very intelligent and I am
>> not sure that I will thoroughly understand the "block" concept.
>
> You need blocks everywhere you need an anonymous callback function such as 
> with iterations:
>
> an_array.each {|e| ... }
>
> And you need lambdas (i.e. blocks converted to an object) if you need to 
> store the thing in a variable:
>
> class SortedArray < Array
> attr_accessor :comparator
> def each
>   sort!(&comparator)
>   super(&b)

I think you need either:

   def each(&b)

or just:

   super  # this seems to propagate the block, at least in 1.8.3
          # (I think this might have changed, but not sure.)


David

-- 
David A. Black
dblack@wobblini.net

"Ruby for Rails", from Manning Publications, coming April 2006!
http://www.manning.com/books/black