On Thu, 15 Dec 2005 14:50:59 +0900, "Daniel Sheppard" <daniels / pronto.com.au> wrote: >I might be wrong - but I'm pretty sure that substrings in ruby are >created with copy-on-write. That is, when you take a substring, a new >block of memory isn't allocated to the new String, it references the >same block of memory as the original string - the allocation of a new >block of memory only occurs when one of the strings is modified. I asked about this a week or two ago, as part of my Extended Set Theory thing, and the impression I got from the answers then was that sub /arrays/ are copy on write but that sub /strings/ were not. I wonder how one might confirm this, other than by asking matz or reading the compiler and libraries ... -- Ron Jeffries www.XProgramming.com I'm giving the best advice I have. You get to decide if it's true for you.