From: Robert Klemme <shortcutter@...>
Date: 2012-02-23T18:20:41+09:00
Subject: Re: cheered to soon enumerable woos

On Thu, Feb 23, 2012 at 9:58 AM, Catsquotl <Catsquotl@gmail.com> wrote:
> What i think is happening is this.
>
> each is called with a block.
> this block iterates over each element of the flattened array.

The block does nothing by itself.  The block is an anonymous callback function.

> But then?
> what does the last call to each(&block) on line 2 do?
>
> when called with a block
> say self.each{|n| puts n}
> nothing seems to happen and the flattened array is returned.

Actually "self" should be returned conventionally.  But that is just a
detail which has nothing to do with iteration.

I can't really believe that nothing happens.  Let's just try this in IRB:

irb(main):001:0> class X
irb(main):002:1> attr_accessor :a, :b, :c
irb(main):003:1> def each(&block)
irb(main):004:2> [a,b,c].flatten.each(&block)
irb(main):005:2> end
irb(main):006:1> end
=> nil
irb(main):007:0> x = X.new
=> #<X:0x202d2bc8>
irb(main):008:0> x.a = 1
=> 1
irb(main):009:0> x.b = 2
=> 2
irb(main):010:0> x.c = 3
=> 3
irb(main):011:0> x.each {|n| puts n}
1
2
3
=> [1, 2, 3]

Now please show your code which does not do anything.

> Can anyone say what's going on?
> I've read up on blocks, procs and lambda's for the last few hours, but I
> can't seem to get to grips with the logic.

The block is simply forwarded to the second call of #each.  Before
that #flatten just ensures that nested Arrays are expanded and every
element of them is visited individually.

>> def each(&block)
>>   [@afk, @name, @chname, @locatie, @aard, @actie].flatten.each(&block)
>> end

Btw. that method should conventionally return "self" at the end.

Kind regards

robert


-- 
remember.guy do |as, often| as.you_can - without end
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