Benchmark reading with and without ||= assignment.

bm_or_equals.rb

# Run 1000000 Times:
#
# ruby 1.8.7 (2010-01-10 patchlevel 249) [x86_64-linux]
#
#   Simple Read : 0.217292 seconds
#     Or Equals : 0.31042 seconds
#
# ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-linux]
#
#   Simple Read : 0.113411725 seconds
#     Or Equals : 0.174376353 seconds

n = 1000000

puts "#{n} Times"

t = Time.now

@b = :b
n.times do
  @b
end

puts "Simple Read : #{Time.now - t} seconds"

t = Time.now

n.times do
  @a ||= :a
end

puts "  Or Equals : #{Time.now - t} seconds"