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| -rw-r--r-- | guides/source/active_support_core_extensions.md | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md index 2ad09f599b..7e6cda4b26 100644 --- a/guides/source/active_support_core_extensions.md +++ b/guides/source/active_support_core_extensions.md @@ -2719,11 +2719,14 @@ The method `transform_keys` accepts a block and returns a hash that has applied # => {"" => nil, "A" => :a, "1" => 1} ``` -The result in case of collision is undefined: +The result in case of key collision is not guaranteed: ```ruby {"a" => 1, a: 2}.transform_keys { |key| key.to_s.upcase } -# => {"A" => 2}, in my test, can't rely on this result though +# The result could either be +# => {"A"=>2} +# or +# => {"A"=>1} ``` This method may be useful for example to build specialized conversions. For instance `stringify_keys` and `symbolize_keys` use `transform_keys` to perform their key conversions: @@ -2758,11 +2761,14 @@ The method `stringify_keys` returns a hash that has a stringified version of the # => {"" => nil, "a" => :a, "1" => 1} ``` -The result in case of collision is undefined: +The result in case of key collision is not guaranteed: ```ruby {"a" => 1, a: 2}.stringify_keys -# => {"a" => 2}, in my test, can't rely on this result though +# The result could either be +# => {"a"=>2} +# or +# => {"a"=>1} ``` This method may be useful for example to easily accept both symbols and strings as options. For instance `ActionView::Helpers::FormHelper` defines: @@ -2799,11 +2805,14 @@ The method `symbolize_keys` returns a hash that has a symbolized version of the WARNING. Note in the previous example only one key was symbolized. -The result in case of collision is undefined: +The result in case of key collision is not guaranteed: ```ruby {"a" => 1, a: 2}.symbolize_keys -# => {:a=>2}, in my test, can't rely on this result though +# The result could either be +# => {:a=>2} +# or +# => {:a=>1} ``` This method may be useful for example to easily accept both symbols and strings as options. For instance `ActionController::UrlRewriter` defines |