class interface DRAWABLE_LINE
creation
   make
feature(s) from DRAWABLE_LINE
   --  Set line definition 
   set_start (pt: POINT)
      --  Set line starting point.
      require
         valid_point: pt /= Void
   set_final (pt: POINT)
      --  Set line ending point (the line will be 
      --  drawn up to but not including this point).
      require
         valid_point: pt /= Void
end of DRAWABLE_LINE