From: dblack@...
Date: 2007-02-22T07:38:19+09:00
Subject: Re: Please illuminate how stupid I am re: initialization blocks.

Hi --

On Thu, 22 Feb 2007, Michael Judge wrote:

> I seem to use blocks much differently from other people and that 
> frightens me a little.  (Maybe I'm being really dumb and nobody wants 
> to say anything.)
>
> Before I get into what I do, let me define how normal people call a 
> block passed in to a method.  They use "yield".  And that's cool, 
> that's what yield is intended for.  Their methods tend to look like 
> this when they're later put into practical use:
>
> create_table :users do |t|
>   t.column :first, :string
>   t.column :last, :string
> end
>
> If I had programmed create_table though, I would have used 
> instance_eval, and you'd use create_table like this:
>
> create_table :users do
> column :first, :string
> column :last, :string
> end
>
> Am I being really dumb?  Is there something horrifying that I'm not 
> grasping?

People do it that way too.  I personally don't like it, because it's
weird to me to have 'self' change in a way that I can't see:

   @x = :first
   create_table :users do
     column @x, :string    # different @x!
   end

I think instance_eval works best as a big clunky method name that
draws attention to itself, and not as something folded away invisibly.


David

-- 
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