Changeset 4489

Timestamp:

06/24/06 16:14:59 (2 years ago)

Author:

david

Message:

Added Enumerable#sum for calculating a sum from the elements [DHH]

Files:

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

trunk/activesupport/CHANGELOG

@@ -1 +1 @@
-*SVN*
+
+* Added Enumerable#sum for calculating a sum from the elements [DHH]. Examples:
+
+    payments.sum { |p| p.price * p.tax_rate }
+    payments.sum(&:price)
+  
+  This is instead of payments.inject(0) { |sum, p| sum + p.price }
-
-* Correct and clarify Array#to_sentence docs.  #5458 [brad@madriska.com]

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

@@ +1 @@
+require File.dirname(__FILE__) + '/enumerable/injections'
+
-module Enumerable #:nodoc:
-  # Collect an enumerable into sets, grouped by the result of a block. Useful,
@@ -21 +23 @@
-    end
-  end 
+
+  # Calculates a sum from the elements. Examples:
+  #
+  #  payments.sum { |p| p.price * p.tax_rate }
+  #  payments.sum(&:price)
+  #
+  # This is instead of payments.inject(0) { |sum, p| sum + p.price }
+  def sum
+    inject(0) { |sum, element| sum + yield(element) }
+  end
-end

trunk/activesupport/test/core_ext/enumerable_test.rb

@@ -2 +2 @@
-require File.dirname(__FILE__) + '/../../lib/active_support/core_ext/enumerable'
-
+Payment = Struct.new(:price)
+
-class EnumerableTests < Test::Unit::TestCase
-  
-  def test_group_by
-    names = %w(marcel sam david jeremy)
@@ -18 +19 @@
-    end
-  end
+  
+  def test_sums
+    payments = [ Payment.new(5), Payment.new(15), Payment.new(10) ]
+    assert_equal 30, payments.sum(&:price)
+    assert_equal 60, payments.sum { |p| p.price * 2 }
+  end
-end