more in 7.2

cookbook/007/02.rb

@@ -1,3 +1,5 @@
+require 'pp'
+
 def call_twice
   puts "Calling your block."
   ret1 = yield("very first")
@@ -12,3 +14,17 @@ call_twice do |which_time|
   puts "I'm a code block, called for the #{which_time} time."
   which_time == "very first" ? 1 : 2
 end
+
+
+class Hash
+  def find_all
+    new_hash = Hash.new
+    each { |k,v| new_hash[k] = v if yield(k, v) }
+    new_hash
+  end
+end
+
+squares = {0=>0, 1=>1, 2=>4, 3=>9}
+print "squares = "
+pp squares
+(squares.find_all { |key, value| key > 1 }).each { |k,v| puts "#{k}: #{v}" }