From: MonkeeSage <MonkeeSage@...>
Date: 2007-11-26T18:05:04+09:00
Subject: Re: specify start postion of Regexp matching

Here's a test to show that my reading of the source, and Robert's
assertion, is correct (there is probably a better way to do this...):

#!/usr/bin/env ruby

# disable GC to get fair reading of actual allocation cost
GC.disable

def free_megs
   (`free -o`.split("\n")[1].split(' ')[3].to_i/1024).to_s
end

puts "Free megabytes " + free_megs
# make a one megabyte string
s1 = "a" * 1048576
s100 = "" # placeholder to be filled in below
# make 100 substrings of it
0.upto(101) { |i| eval("s#{i}=s1[0..-1]") }

puts s100.length.to_s
puts "Free megabytes " + free_megs

Output:

Free megabytes 588
1048576
Free megabytes 587

Only one meg is used, which is the length of the original string. So,
by inductive inference, the substrings are only pointers back to the
original string rather than copies of the data.

Regards,
Jordan