From: RichardOnRails <RichardDummyMailbox58407@...>
Date: 2009-11-05T05:30:06+09:00
Subject: Re: Ruby doesn't implement x++ for Fixnum's because ???

On Nov 4, 2:13 pm, Seebs <usenet-nos...@seebs.net> wrote:
> On 2009-11-04, RichardOnRails <RichardDummyMailbox58...@USComputerGurus.com> wrote:
>
> > class Fixnum
> >   def pp # We can?t define ++ because of a compiler restriction.
> >     self + 1
> >   end
> > end
>
> This doesn't seem to do the right thing.
>
> a = 1
> a.pp
>
> Is a now 2?  If not, you haven't implemented an increment operator.
>
> > Appending these  lines shows that a & b values are distinct.
> > That is,  after incrementing,  a =2,  b is unchanged; b is not
> > impacted by a?s change
> > a += 1; show (a)  =>  Got 2;  class = Fixnum;   object_id = 5;  v >> 1
> >= 2
> > show (b)  =>  Got 1;  class = Fixnum;   object_id = 3;  v >> 1 = 1
>
> Right.  You've changed which object a refers to, because you've reassigned
> a.
>
> > Appending these  lines shows the ++?s alias pp works just find
> > a=1; show(a.pp)  =>  Got 2;  class = Fixnum;   object_id = 5;  v >> 1
> >= 2
> > show(b)  =>  Got 1;  class = Fixnum;   object_id = 3;  v >> 1 = 1
>
> Not the same.  The key is that, after "a += 1", not only do you get 2,
> but a is now 2.
>
> > Do you agree?
>
> No.
>
> For "a.pp" to be the same as a++ in other languages, you'd have to do:
>
> a = 1; a.pp; show(a) => Got 2
>
> If you don't get a "2" by using a.pp, it's not an increment, just a "one
> more than".
>
> Consider a loop:
>
> a = 1
> while ((a += 1) < 10) do
>   puts a
> end
>
> Now, try:
>
> a = 1
> while (a.pp < 10) do
>   puts a
> end
>
> Doesn't do the same thing.
>
> -s
> --
> Copyright 2009, all wrongs reversed.  Peter Seebach / usenet-nos...@seebs.nethttp://www.seebs.net/log/<-- lawsuits, religion, and funny pictureshttp://en.wikipedia.org/wiki/Fair_Game_(Scientology) <-- get educated!

Hi Peter,

> This doesn't seem to do the right thing.
>
> a = 1
> a.pp
>
> Is a now 2?  If not, you haven't implemented an increment operator.

Thanks for this question.  You're so right.  I couldn't see it until
you pointed it out.

class Fixnum
  def pp # We can’t define ++ because of a compiler restriction.
    self + 1
  end
end

doesn't change self (which Ruby won't allow for Fixnum's!!!  Which, of
course, is why your:

a = 1
while (a.pp < 10) do
  puts a
end

produces an infinite number of 1's ..., or would if RAM were infinite
and hardware addressing mechanisms were infinite.

I grateful for you taking the time to identify my deficiencies.

Best wishes,
Richard