Add examples for Hash vs OpenStruct

- compares creation
- compares access
- update README.md

Closes #38

Author: ablignaut

README.md

@@ -225,6 +225,42 @@ allows one to define and raise exceptions with predefined messages.
 
 ```
 
+##### Hash vs OpenStruct on access assuming you already have a Hash or an OpenStruct [code](code/general/hash-vs-openstruct-on-access.rb)
+
+```
+$ ruby -v code/general/hash-vs-openstruct-on-access.rb
+ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14]
+
+Calculating -------------------------------------
+                Hash   128.344k i/100ms
+          OpenStruct   110.723k i/100ms
+-------------------------------------------------
+                Hash      5.279M (± 7.0%) i/s -     26.311M
+          OpenStruct      3.048M (± 7.0%) i/s -     15.169M
+
+Comparison:
+                Hash:  5278844.0 i/s
+          OpenStruct:  3048139.8 i/s - 1.73x slower
+```
+
+##### Hash vs OpenStruct (creation) [code](code/general/hash-vs-openstruct.rb)
+
+```
+$ ruby -v code/general/hash-vs-openstruct.rb
+ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14]
+
+Calculating -------------------------------------
+                Hash    75.510k i/100ms
+          OpenStruct     9.126k i/100ms
+-------------------------------------------------
+                Hash      1.604M (±11.0%) i/s -      7.929M
+          OpenStruct     96.855k (± 9.9%) i/s -    483.678k
+
+Comparison:
+                Hash:  1604259.1 i/s
+          OpenStruct:    96855.3 i/s - 16.56x slower
+```
+
 ### Array
 
 ##### `Array#bsearch` vs `Array#find` [code](code/array/bsearch-vs-find.rb)

code/general/hash-vs-openstruct-on-access.rb

@@ -0,0 +1,19 @@
+require "benchmark/ips"
+require "ostruct"
+
+ HASH = { field_1: 1, field_2: 2}
+ OPENSTRUCT = OpenStruct.new(field_1: 1, field_2: 2)
+
+def fast
+  [HASH[:field_1], HASH[:field_2]]
+end
+
+def slow
+  [OPENSTRUCT.field_1, OPENSTRUCT.field_2]
+end
+
+Benchmark.ips do |x|
+  x.report("Hash")       { fast }
+  x.report("OpenStruct") { slow }
+  x.compare!
+end

code/general/hash-vs-openstruct.rb

@@ -0,0 +1,16 @@
+require "benchmark/ips"
+require "ostruct"
+
+def fast
+  { field_1: 1, field_2: 2 }
+end
+
+def slow
+  OpenStruct.new(field_1: 1, field_2: 2)
+end
+
+Benchmark.ips do |x|
+  x.report("Hash")       { fast }
+  x.report("OpenStruct") { slow }
+  x.compare!
+end