From: Len Lawrence <lcl@...>
Date: 2008-03-22T22:14:52+09:00
Subject: Cloning arrays

Another newbie question.  I have started recoding some of my homegrown
Tcl/Tk applications in Ruby/rubytk and have hit an unexpected snag when
attempting to clone arrays.  The following code is snipped verbatim from
the program:

  # Calculate coordinates for the Postscript page canvas and the
  # label icons canvas in the setupInkjet window.

  def User.calcxy ( disposition, f )

    xygrid = { }

    # Split the disposition string into x and y counts.    
    xy = Typefaces::Disposition[disposition]
    # Obtain the label dimensions.
    labelsize = Typefaces::Labelsizes[disposition]
    # Populate the coordinate data structure.
    xygrid['x']  = nx = xy[0]
    xygrid['y']  = ny = xy[1]
    xygrid['dx'] = dx = labelsize[0] * f
    xygrid['dy'] = dy = labelsize[1] * f
    # Obtain an array of 4 element arrays from the Typefaces module.
    # These represent opposing corners of the address spaces on the
    # Postscript canvas. 
    xygrid['page'] = Typefaces.labelgrid( disposition )
    puts 'page coordinates'
    puts xygrid['page'][0]
    puts '______________'
    # Copy the page label coordinates.
    e = xygrid['page'].clone
    # Shrink the label icon coordinates.
    e.each { |z| z.collect! { |d| d *= f } }
    # Shrink the icons further to make separations visible.
    e.each { |z| z[2] -= 2.0; z[3] -= 2.0 }
    # Save the label icon coordinates.
    xygrid['boxes'] = e
    puts 'page again'
    puts xygrid['page'][0]
    puts 'boxes'
    puts e[0]
    puts '=============='
    xygrid['max'] = nx * ny
    return xygrid

  end

The diagnostics at 'page again' and 'boxes' show that the copy of the
original array has been successfully processed but the original array now
reflects the same values.  The 'page' and 'boxes' arrays are to be used in
different circumstances.  

What am I missing?  It is bound to be something simple or something
fundamental.  I tried Object#dup also - same result.

Len