Changeset 4491

Timestamp:

06/24/06 16:42:48 (3 years ago)

Author:

ulysses

Message:

Add Enumerable#index_by

Files:

• trunk/activesupport/lib/active_support/core_ext/enumerable.rb (modified) (1 diff)
• trunk/activesupport/test/core_ext/enumerable_test.rb (modified) (2 diffs)

trunk/activesupport/lib/active_support/core_ext/enumerable.rb

@@ -31 +31 @@
-    inject(0) { |sum, element| sum + yield(element) }
-  end
+  
+  # Convert an enumerable to a hash. Examples:
+  # 
+  #   people.index_by(&:login)
+  #     => { "nextangle" => <Person ...>, "chade-" => <Person ...>, ...}
+  #   people.index_by { |person| "#{person.first_name} #{person.last_name}" }
+  #     => { "Chade- Fowlersburg-e" => <Person ...>, "David Heinemeier Hansson" => <Person ...>, ...}
+  # 
+  def index_by
+    inject({}) do |accum, elem|
+      accum[yield(elem)] = elem
+      accum
+    end
+  end
+  
-end

trunk/activesupport/test/core_ext/enumerable_test.rb

@@ -1 +1 @@
-require 'test/unit'
+require File.dirname(__FILE__) + '/../../lib/active_support/core_ext/symbol'
-require File.dirname(__FILE__) + '/../../lib/active_support/core_ext/enumerable'
-
@@ -25 +26 @@
-    assert_equal 60, payments.sum { |p| p.price * 2 }
-  end
+  
+  def test_index_by
+    payments = [ Payment.new(5), Payment.new(15), Payment.new(10) ]
+    assert_equal(
+      {5 => payments[0], 15 => payments[1], 10 => payments[2]},
+      payments.index_by(&:price)
+    )
+  end
+  
-end