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| author | Jeremy Kemper <jeremy@bitsweat.net> | 2006-07-09 20:48:31 +0000 |
|---|---|---|
| committer | Jeremy Kemper <jeremy@bitsweat.net> | 2006-07-09 20:48:31 +0000 |
| commit | 5241b97709c693f272d457abc9165e7d750330b3 (patch) | |
| tree | aceed61edcbc803208046a74ccd5a5d19683ae5f | |
| parent | 1dc4cc030ffecb57ceffecac81215ed1d7924f3f (diff) | |
| download | rails-5241b97709c693f272d457abc9165e7d750330b3.tar.gz rails-5241b97709c693f272d457abc9165e7d750330b3.tar.bz2 rails-5241b97709c693f272d457abc9165e7d750330b3.zip | |
Optional identity for Enumerable#sum defaults to zero. Closes #5657.
git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4599 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
| -rw-r--r-- | activesupport/CHANGELOG | 2 | ||||
| -rw-r--r-- | activesupport/lib/active_support/core_ext/enumerable.rb | 9 | ||||
| -rw-r--r-- | activesupport/test/core_ext/enumerable_test.rb | 8 |
3 files changed, 17 insertions, 2 deletions
diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG index 62450807c2..5d79c19385 100644 --- a/activesupport/CHANGELOG +++ b/activesupport/CHANGELOG @@ -1,5 +1,7 @@ *SVN* +* Optional identity for Enumerable#sum defaults to zero. #5657 [gensym@mac.com] + * HashWithIndifferentAccess shouldn't confuse false and nil. #5601 [shugo@ruby-lang.org] * Fixed HashWithIndifferentAccess#default #5586 [chris@seagul.co.uk] diff --git a/activesupport/lib/active_support/core_ext/enumerable.rb b/activesupport/lib/active_support/core_ext/enumerable.rb index 92304a23f6..59128007df 100644 --- a/activesupport/lib/active_support/core_ext/enumerable.rb +++ b/activesupport/lib/active_support/core_ext/enumerable.rb @@ -30,7 +30,14 @@ module Enumerable #:nodoc: # # Also calculates sums without the use of a block: # [5, 15, 10].sum # => 30 - def sum(&block) + # + # The default identity (sum of an empty list) is zero. + # However, you can override this default: + # + # [].sum(Payment.new(0)) { |i| i.amount } # => Payment.new(0) + # + def sum(identity = 0, &block) + return identity unless size > 0 if block_given? map(&block).sum else diff --git a/activesupport/test/core_ext/enumerable_test.rb b/activesupport/test/core_ext/enumerable_test.rb index 3180755e5f..0590846b7b 100644 --- a/activesupport/test/core_ext/enumerable_test.rb +++ b/activesupport/test/core_ext/enumerable_test.rb @@ -44,7 +44,13 @@ class EnumerableTests < Test::Unit::TestCase assert_raise(TypeError) { payments.sum(&:price) } assert_equal 60, payments.sum { |p| p.price.to_i * 2 } end - + + def test_empty_sums + assert_equal 0, [].sum + assert_equal 0, [].sum { |i| i } + assert_equal Payment.new(0), [].sum(Payment.new(0)) + end + def test_index_by payments = [ Payment.new(5), Payment.new(15), Payment.new(10) ] assert_equal( |