From: Robert Klemme <bob.news@...>
Date: 2004-10-13T00:34:35+09:00
Subject: Re: Ruby Directions (was Re: quality of error messages)


"Markus" <markus@reality.com> schrieb im Newsbeitrag
news:1097593941.20674.27.camel@lapdog.reality.com...
> On Tue, 2004-10-12 at 00:09, Robert Klemme wrote:
> > Regardless of whether Ranges should rather be immutable or not, I
plead
> > for sticking with the current immutability.  The reason is simply that
a
> > change of mutability of a class is a major change, which is likely to
> > break a lot of code.  Everybody that relied on a Range being immutable
and
> > thus stored an instance as member of his own classes might recognize
the
> > range suddenly changed when it's no longer immutable.
>
>      I'm not sure I understand your point; could you provide an example
> of how this might happen?  Specifically, how code that did not attempt
> to modify something would be affected if it became, in theory, possible
> to modify it.  Or am I misunderstanding?

class Demo < Struct.new(:range)
  def show
    range.each {|val| puts val}
  end
end

r = 1..10
d = Demo.new r
d.show
# modify r in place
d.show

In this scenario the second "d.show" will unexpectedly print something
else if r could be modified in place.

Kind regards

    robert