From: HarryO <harryo@...>
Date: 2001-11-16T22:27:18+09:00
Subject: [ruby-talk:25422] Re: Redefining Fixnum.x(val)?

In article <002501c16e99$125cae40$6329c6c3@telia.com>, "Henning von Rosen"
<henning@ikso.net> wrote:

> It works just fine, the first time I run it. If it is run a second time,
> in the same interpreter, then the old and new plus gets identical, and
> the result is an infinte loop. When running the script from the command
> line, there should be no problem.

The problem is that the second time, Fixnum#+() is already your new
definition, so when you create the alias it's aliasing to the same
method.

In practice, this would not happen, except that you are re-running the
same code inside the same interpreter, as you say.

You can avoid the problem by adding a test around the alias creation,
like this ...

  if !defined? oldPlus
     alias oldAlias +
  end

> What do you use for running the program?

I put the code in a file, say "fred.rb" then run the command "ruby
fred.rb".  In this case, each time I run the code it's in a new copy of
the interpreter, so this kind of problem doesn't occur.

Hope that helps.