From: Robert Klemme <shortcutter@...>
Date: 2012-04-06T07:00:56+09:00
Subject: Re: Call for comments - Structure

On Thu, Apr 5, 2012 at 5:18 PM, Hal Fulton <rubyhacker@gmail.com> wrote:
> 2012/4/5 Robert Klemme <shortcutter@googlemail.com>
>>
>> On Thu, Apr 5, 2012 at 4:33 PM, Bartosz Dziewoński <matma.rex@gmail.com>
>> wrote:> Struct just does not have instance variables, which is surprising,
>>
>> I know - that's the whole point why "#instance_variables returns an
>> empty list".  But the question was, whether this is the reason Hal
>> calls them "unreal" - and whether it matters.  Both can probably only
>> be answered by him since he coined the phrase...
>>
>> > if you assume that "Point = Struct :x, :y" is a shorthand for "class
>> > Point; attr_accessor :x, :y; def initialize x, y; @x, @y = x, y; end;
>> > end".
>>
>> Well, obviously it is not a shorthand for the code you show. :-)
>> Still it doesn't explain why Hal calls them "unreal".  We are still
>> only guessing as to what intentions his might have been.
>
> Bartosz has understood my point. I don't mind that instance_variables
> returns an empty list, but I have been annoyed at the difficulty or
> impossibility
> of reopening the class to add useful methods that manipulate the
> instance data.

That I don't understand, maybe that's the reason for the previous
discussion: for me it is fairly easy and straightforward

Counter = Struct.new :value do
  def incr(x = 1)
    self.value += x
  end

  alias to_i value
end

I find that neither difficult nor impossible.  What did you have in mind?

> It would not be the first time I tried to solve a problem that many or most
> others did not perceive at all.

:-)

Cheers

robert

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