diff options
Diffstat (limited to 'guides/source/active_support_core_extensions.md')
| -rw-r--r-- | guides/source/active_support_core_extensions.md | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md index 565c87c4b5..70b04a9695 100644 --- a/guides/source/active_support_core_extensions.md +++ b/guides/source/active_support_core_extensions.md @@ -368,7 +368,7 @@ account.to_query('company[name]') so its output is ready to be used in a query string. -Arrays return the result of applying `to_query` to each element with `_key_[]` as key, and join the result with "&": +Arrays return the result of applying `to_query` to each element with `key[]` as key, and join the result with "&": ```ruby [3.4, -45.6].to_query('sample') @@ -954,7 +954,8 @@ class A class_attribute :x, instance_reader: false end -A.new.x = 1 # NoMethodError +A.new.x = 1 +A.new.x # NoMethodError ``` For convenience `class_attribute` also defines an instance predicate which is the double negation of what the instance reader returns. In the examples above it would be called `x?`. @@ -2035,7 +2036,7 @@ Addition only assumes the elements respond to `+`: ```ruby [[1, 2], [2, 3], [3, 4]].sum # => [1, 2, 2, 3, 3, 4] %w(foo bar baz).sum # => "foobarbaz" -{a: 1, b: 2, c: 3}.sum # => [:b, 2, :c, 3, :a, 1] +{a: 1, b: 2, c: 3}.sum # => [:b, 2, :c, 3, :a, 1] ``` The sum of an empty collection is zero by default, but this is customizable: @@ -2660,7 +2661,7 @@ The method `transform_keys` accepts a block and returns a hash that has applied ```ruby {nil => nil, 1 => 1, a: :a}.transform_keys { |key| key.to_s.upcase } -# => {"" => nil, "A" => :a, "1" => 1} +# => {"" => nil, "1" => 1, "A" => :a} ``` In case of key collision, one of the values will be chosen. The chosen value may not always be the same given the same hash: @@ -2702,7 +2703,7 @@ The method `stringify_keys` returns a hash that has a stringified version of the ```ruby {nil => nil, 1 => 1, a: :a}.stringify_keys -# => {"" => nil, "a" => :a, "1" => 1} +# => {"" => nil, "1" => 1, "a" => :a} ``` In case of key collision, one of the values will be chosen. The chosen value may not always be the same given the same hash: @@ -2744,7 +2745,7 @@ The method `symbolize_keys` returns a hash that has a symbolized version of the ```ruby {nil => nil, 1 => 1, "a" => "a"}.symbolize_keys -# => {1=>1, nil=>nil, :a=>"a"} +# => {nil=>nil, 1=>1, :a=>"a"} ``` WARNING. Note in the previous example only one key was symbolized. @@ -2821,7 +2822,7 @@ Ruby has built-in support for taking slices out of strings and arrays. Active Su ```ruby {a: 1, b: 2, c: 3}.slice(:a, :c) -# => {:c=>3, :a=>1} +# => {:a=>1, :c=>3} {a: 1, b: 2, c: 3}.slice(:b, :X) # => {:b=>2} # non-existing keys are ignored @@ -2915,6 +2916,24 @@ end NOTE: Defined in `active_support/core_ext/regexp.rb`. +### `match?` + +Rails implements `Regexp#match?` for Ruby versions prior to 2.4: + +```ruby +/oo/.match?('foo') # => true +/oo/.match?('bar') # => false +/oo/.match?('foo', 1) # => true +``` + +The backport has the same interface and lack of side-effects in the caller like +not setting `$1` and friends, but it does not have the speed benefits. Its +purpose is to be able to write 2.4 compatible code. Rails itself uses this +predicate internally for example. + +Active Support defines `Regexp#match?` only if not present, so code running +under 2.4 or later does run the original one and gets the performance boost. + Extensions to `Range` --------------------- |