From: Ilias Lazaridis <ilias@...>
Date: 2005-04-03T22:04:43+09:00
Subject: Re: [EVALUATION] - E03 - jamLang Evaluation Case Applied to Ruby

Anders Engstr�m wrote:
> On Sun, Apr 03, 2005 at 08:39:42PM +0900, Ilias Lazaridis wrote:
> [snipp]
> 
>>But to understand this fully, can someone please decrypt this:
>>
>>  def meta()
>>    @meta ||= {}
>>  end
> 
> That's lazy initialization of the @meta variable. Another (and more
> verbose) way to write it would be:
> 
> def meta()
>     unless @meta #If not defined, set the value
>         @meta = {}
>     end
>     @meta # Return Meta
> end

def meta()      # use of "()" is optional
   unless @meta  # if @meta == nil  (unless = if not)
     @meta = {}  # creates a new hash
   end
   @meta         # returns the (existing or new) hash
end

> "@meta ||= {}" evaluates to "@meta = @meta || {}" and since the returned

"||=" similar to "+="

"||" means: if left operand is nil, pick right operand.

> value from a method is the last evaluated expression "@meta ||= {}"
> works.

ok, got it!

[will update the document soon - and hopefully can soon take the next round]

> //Anders

..

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