From: "Ara.T.Howard" <ahoward@...>
Date: 2004-08-06T03:31:27+09:00
Subject: Re: Macros in Ruby

On Fri, 6 Aug 2004, Austin Ziegler wrote:

> On Fri, 6 Aug 2004 01:31:28 +0900, Ara.T.Howard <ahoward@noaa.gov> wrote:
>> i actually use them quite a bit and would appreciate a shortcut. i sometimes
>> prefer to have modifiable Proc attributes of object to parameterize their
>> behaviour rather than messing with inheritence or dynamic redefinition. i
>> also end up writing methods which take options callbacks for
>> debugging/logging, eg:
>
> I'd do this as:
>
>  def long_db_update(arg, callback = nil)
>    sql = gen_sql(arg)
>
>    callback.pre(sql) if callback.respond_to?(:pre)
>
>    res =
>      if callback.respond_to?(:pan)
> 	t = Thread.new(Thread.current) do |c|
> 	  begin
> 	    execute(sql)
> 	  rescue => e
> 	    c.raise (e)
> 	  end
> 	end
>
> 	loop do
> 	  break unless t.status
> 	  callback.pan(get_state)
> 	  sleep 0.42
> 	end
>
> 	t.join
> 	t.value
>      else
> 	execute(sql)
>      end
>
>    callback.post(res) if callback.respond_to?(:post)
>    res
>  end
>
> Then I can create my callback object. With this, I could easily plug
> in a debug object (predefined), a GUI object, or anything else, and
> my callback becomes part of my defined API. (I would actually even
> go as far as modifying callback.post so that its return may
> optionally modify res.)
>
> -austin
> --
> Austin Ziegler * halostatue@gmail.com
>               * Alternate: austin@halostatue.ca
>

ducktype madness!  ;-)

sure, that's alot better than my way - i'm just pointing out that some of us
type 'l-a-m-b-d-a' alot and consider them an undervalued technique for
creating flexible objects since they may easily blur the line between
attributes and behaviour (not that ruby is lacking in flexibility!).

cheers.

-a
--
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| PHONE   :: 303.497.6469
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| and a weed grows, even though we do not love it. 
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