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Diffstat (limited to 'guides/source/active_support_core_extensions.md')
| -rw-r--r-- | guides/source/active_support_core_extensions.md | 390 |
1 files changed, 166 insertions, 224 deletions
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md index 1438245f9c..ae2e1faf14 100644 --- a/guides/source/active_support_core_extensions.md +++ b/guides/source/active_support_core_extensions.md @@ -135,16 +135,14 @@ NOTE: Defined in `active_support/core_ext/object/blank.rb`. ### `duplicable?` -In Ruby 2.4 most objects can be duplicated via `dup` or `clone` except -methods and certain numbers. Though Ruby 2.2 and 2.3 can't duplicate `nil`, -`false`, `true`, and symbols as well as instances `Float`, `Fixnum`, -and `Bignum` instances. +As of Ruby 2.5, most objects can be duplicated via `dup` or `clone`: ```ruby "foo".dup # => "foo" "".dup # => "" -1.method(:+).dup # => TypeError: allocator undefined for Method -Complex(0).dup # => TypeError: can't copy Complex +Rational(1).dup # => (1/1) +Complex(0).dup # => (0+0i) +1.method(:+).dup # => TypeError (allocator undefined for Method) ``` Active Support provides `duplicable?` to query an object about this: @@ -152,35 +150,18 @@ Active Support provides `duplicable?` to query an object about this: ```ruby "foo".duplicable? # => true "".duplicable? # => true -Rational(1).duplicable? # => false -Complex(1).duplicable? # => false +Rational(1).duplicable? # => true +Complex(1).duplicable? # => true 1.method(:+).duplicable? # => false ``` -`duplicable?` matches Ruby's `dup` according to the Ruby version. - -So in 2.4: - -```ruby -nil.dup # => nil -:my_symbol.dup # => :my_symbol -1.dup # => 1 - -nil.duplicable? # => true -:my_symbol.duplicable? # => true -1.duplicable? # => true -``` - -Whereas in 2.2 and 2.3: +`duplicable?` matches the current Ruby version's `dup` behavior, +so results will vary according the version of Ruby you're using. +In Ruby 2.4, for example, Complex and Rational are not duplicable: ```ruby -nil.dup # => TypeError: can't dup NilClass -:my_symbol.dup # => TypeError: can't dup Symbol -1.dup # => TypeError: can't dup Fixnum - -nil.duplicable? # => false -:my_symbol.duplicable? # => false -1.duplicable? # => false +Rational(1).duplicable? # => false +Complex(1).duplicable? # => false ``` WARNING: Any class can disallow duplication by removing `dup` and `clone` or raising exceptions from them. Thus only `rescue` can tell whether a given arbitrary object is duplicable. `duplicable?` depends on the hard-coded list above, but it is much faster than `rescue`. Use it only if you know the hard-coded list is enough in your use case. @@ -674,44 +655,6 @@ M.parents # => [X::Y, X, Object] NOTE: Defined in `active_support/core_ext/module/introspection.rb`. -### Reachable - -A named module is reachable if it is stored in its corresponding constant. It means you can reach the module object via the constant. - -That is what ordinarily happens, if a module is called "M", the `M` constant exists and holds it: - -```ruby -module M -end - -M.reachable? # => true -``` - -But since constants and modules are indeed kind of decoupled, module objects can become unreachable: - -```ruby -module M -end - -orphan = Object.send(:remove_const, :M) - -# The module object is orphan now but it still has a name. -orphan.name # => "M" - -# You cannot reach it via the constant M because it does not even exist. -orphan.reachable? # => false - -# Let's define a module called "M" again. -module M -end - -# The constant M exists now again, and it stores a module -# object called "M", but it is a new instance. -orphan.reachable? # => false -``` - -NOTE: Defined in `active_support/core_ext/module/reachable.rb`. - ### Anonymous A module may or may not have a name: @@ -745,7 +688,6 @@ end m = Object.send(:remove_const, :M) -m.reachable? # => false m.anonymous? # => false ``` @@ -837,6 +779,14 @@ delegate :size, to: :attachment, prefix: :avatar In the previous example the macro generates `avatar_size` rather than `size`. +The option `:private` changes methods scope: + +```ruby +delegate :date_of_birth, to: :profile, private: true +``` + +The delegated methods are public by default. Pass `private: true` to change that. + NOTE: Defined in `active_support/core_ext/module/delegation.rb` #### `delegate_missing_to` @@ -964,6 +914,15 @@ The macros `cattr_reader`, `cattr_writer`, and `cattr_accessor` are analogous to ```ruby class MysqlAdapter < AbstractAdapter # Generates class methods to access @@emulate_booleans. + cattr_accessor :emulate_booleans +end +``` + +Also, you can pass a block to `cattr_*` to set up the attribute with a default value: + +```ruby +class MysqlAdapter < AbstractAdapter + # Generates class methods to access @@emulate_booleans with default value of true. cattr_accessor :emulate_booleans, default: true end ``` @@ -980,15 +939,6 @@ end we can access `field_error_proc` in views. -Also, you can pass a block to `cattr_*` to set up the attribute with a default value: - -```ruby -class MysqlAdapter < AbstractAdapter - # Generates class methods to access @@emulate_booleans with default value of true. - cattr_accessor :emulate_booleans, default: true -end -``` - The generation of the reader instance method can be prevented by setting `:instance_reader` to `false` and the generation of the writer instance method can be prevented by setting `:instance_writer` to `false`. Generation of both methods can be prevented by setting `:instance_accessor` to `false`. In all cases, the value must be exactly `false` and not any false value. ```ruby @@ -1791,7 +1741,7 @@ The methods `to_date`, `to_time`, and `to_datetime` are basically convenience wr "2010-07-27 23:42:00".to_time(:local) # => 2010-07-27 23:42:00 +0200 ``` -Default is `:utc`. +Default is `:local`. Please refer to the documentation of `Date._parse` for further details. @@ -1835,7 +1785,7 @@ NOTE: Defined in `active_support/core_ext/numeric/bytes.rb`. ### Time -Enables the use of time calculations and declarations, like `45.minutes + 2.hours + 4.years`. +Enables the use of time calculations and declarations, like `45.minutes + 2.hours + 4.weeks`. These methods use Time#advance for precise date calculations when using from_now, ago, etc. as well as adding or subtracting their results from a Time object. For example: @@ -1844,13 +1794,15 @@ as well as adding or subtracting their results from a Time object. For example: # equivalent to Time.current.advance(months: 1) 1.month.from_now -# equivalent to Time.current.advance(years: 2) -2.years.from_now +# equivalent to Time.current.advance(weeks: 2) +2.weeks.from_now -# equivalent to Time.current.advance(months: 4, years: 5) -(4.months + 5.years).from_now +# equivalent to Time.current.advance(months: 4, weeks: 5) +(4.months + 5.weeks).from_now ``` +WARNING. For other durations please refer to the time extensions to `Integer`. + NOTE: Defined in `active_support/core_ext/numeric/time.rb`. ### Formatting @@ -1986,6 +1938,28 @@ The method `ordinalize` returns the ordinal string corresponding to the receiver NOTE: Defined in `active_support/core_ext/integer/inflections.rb`. +### Time + +Enables the use of time calculations and declarations, like `4.months + 5.years`. + +These methods use Time#advance for precise date calculations when using from_now, ago, etc. +as well as adding or subtracting their results from a Time object. For example: + +```ruby +# equivalent to Time.current.advance(months: 1) +1.month.from_now + +# equivalent to Time.current.advance(years: 2) +2.years.from_now + +# equivalent to Time.current.advance(months: 4, years: 5) +(4.months + 5.years).from_now +``` + +WARNING. For other durations please refer to the time extensions to `Numeric`. + +NOTE: Defined in `active_support/core_ext/integer/time.rb`. + Extensions to `BigDecimal` -------------------------- ### `to_s` @@ -1993,19 +1967,19 @@ Extensions to `BigDecimal` The method `to_s` provides a default specifier of "F". This means that a simple call to `to_s` will result in floating point representation instead of engineering notation: ```ruby -BigDecimal.new(5.00, 6).to_s # => "5.0" +BigDecimal(5.00, 6).to_s # => "5.0" ``` and that symbol specifiers are also supported: ```ruby -BigDecimal.new(5.00, 6).to_s(:db) # => "5.0" +BigDecimal(5.00, 6).to_s(:db) # => "5.0" ``` Engineering notation is still supported: ```ruby -BigDecimal.new(5.00, 6).to_s("e") # => "0.5E1" +BigDecimal(5.00, 6).to_s("e") # => "0.5E1" ``` Extensions to `Enumerable` @@ -2791,20 +2765,6 @@ Active Record does not accept unknown options when building associations, for ex NOTE: Defined in `active_support/core_ext/hash/keys.rb`. -### Working with Values - -#### `transform_values` && `transform_values!` - -The method `transform_values` accepts a block and returns a hash that has applied the block operations to each of the values in the receiver. - -```ruby -{ nil => nil, 1 => 1, :x => :a }.transform_values { |value| value.to_s.upcase } -# => {nil=>"", 1=>"1", :x=>"A"} -``` -There's also the bang variant `transform_values!` that applies the block operations to values in the very receiver. - -NOTE: Defined in `active_support/core_ext/hash/transform_values.rb`. - ### Slicing Ruby has built-in support for taking slices out of strings and arrays. Active Support extends slicing to hashes: @@ -2866,16 +2826,6 @@ The method `with_indifferent_access` returns an `ActiveSupport::HashWithIndiffer NOTE: Defined in `active_support/core_ext/hash/indifferent_access.rb`. -### Compacting - -The methods `compact` and `compact!` return a Hash without items with `nil` value. - -```ruby -{a: 1, b: 2, c: nil}.compact # => {a: 1, b: 2} -``` - -NOTE: Defined in `active_support/core_ext/hash/compact.rb`. - Extensions to `Regexp` ---------------------- @@ -2905,24 +2855,6 @@ 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` --------------------- @@ -2985,6 +2917,32 @@ Extensions to `Date` NOTE: All the following methods are defined in `active_support/core_ext/date/calculations.rb`. +```ruby +yesterday +tomorrow +beginning_of_week (at_beginning_of_week) +end_of_week (at_end_of_week) +monday +sunday +weeks_ago +prev_week (last_week) +next_week +months_ago +months_since +beginning_of_month (at_beginning_of_month) +end_of_month (at_end_of_month) +last_month +beginning_of_quarter (at_beginning_of_quarter) +end_of_quarter (at_end_of_quarter) +beginning_of_year (at_beginning_of_year) +end_of_year (at_end_of_year) +years_ago +years_since +last_year +on_weekday? +on_weekend? +``` + INFO: The following calculation methods have edge cases in October 1582, since days 5..14 just do not exist. This guide does not document their behavior around those days for brevity, but it is enough to say that they do what you would expect. That is, `Date.new(1582, 10, 4).tomorrow` returns `Date.new(1582, 10, 15)` and so on. Please check `test/core_ext/date_ext_test.rb` in the Active Support test suite for expected behavior. #### `Date.current` @@ -2995,68 +2953,6 @@ When making Date comparisons using methods which honor the user time zone, make #### Named dates -##### `prev_year`, `next_year` - -In Ruby 1.9 `prev_year` and `next_year` return a date with the same day/month in the last or next year: - -```ruby -d = Date.new(2010, 5, 8) # => Sat, 08 May 2010 -d.prev_year # => Fri, 08 May 2009 -d.next_year # => Sun, 08 May 2011 -``` - -If date is the 29th of February of a leap year, you obtain the 28th: - -```ruby -d = Date.new(2000, 2, 29) # => Tue, 29 Feb 2000 -d.prev_year # => Sun, 28 Feb 1999 -d.next_year # => Wed, 28 Feb 2001 -``` - -`prev_year` is aliased to `last_year`. - -##### `prev_month`, `next_month` - -In Ruby 1.9 `prev_month` and `next_month` return the date with the same day in the last or next month: - -```ruby -d = Date.new(2010, 5, 8) # => Sat, 08 May 2010 -d.prev_month # => Thu, 08 Apr 2010 -d.next_month # => Tue, 08 Jun 2010 -``` - -If such a day does not exist, the last day of the corresponding month is returned: - -```ruby -Date.new(2000, 5, 31).prev_month # => Sun, 30 Apr 2000 -Date.new(2000, 3, 31).prev_month # => Tue, 29 Feb 2000 -Date.new(2000, 5, 31).next_month # => Fri, 30 Jun 2000 -Date.new(2000, 1, 31).next_month # => Tue, 29 Feb 2000 -``` - -`prev_month` is aliased to `last_month`. - -##### `prev_quarter`, `next_quarter` - -Same as `prev_month` and `next_month`. It returns the date with the same day in the previous or next quarter: - -```ruby -t = Time.local(2010, 5, 8) # => Sat, 08 May 2010 -t.prev_quarter # => Mon, 08 Feb 2010 -t.next_quarter # => Sun, 08 Aug 2010 -``` - -If such a day does not exist, the last day of the corresponding month is returned: - -```ruby -Time.local(2000, 7, 31).prev_quarter # => Sun, 30 Apr 2000 -Time.local(2000, 5, 31).prev_quarter # => Tue, 29 Feb 2000 -Time.local(2000, 10, 31).prev_quarter # => Mon, 30 Oct 2000 -Time.local(2000, 11, 31).next_quarter # => Wed, 28 Feb 2001 -``` - -`prev_quarter` is aliased to `last_quarter`. - ##### `beginning_of_week`, `end_of_week` The methods `beginning_of_week` and `end_of_week` return the dates for the @@ -3174,6 +3070,8 @@ Date.new(2012, 2, 29).years_ago(3) # => Sat, 28 Feb 2009 Date.new(2012, 2, 29).years_since(3) # => Sat, 28 Feb 2015 ``` +`last_year` is short-hand for `#years_ago(1)`. + ##### `months_ago`, `months_since` The methods `months_ago` and `months_since` work analogously for months: @@ -3190,6 +3088,8 @@ Date.new(2010, 4, 30).months_ago(2) # => Sun, 28 Feb 2010 Date.new(2009, 12, 31).months_since(2) # => Sun, 28 Feb 2010 ``` +`last_month` is short-hand for `#months_ago(1)`. + ##### `weeks_ago` The method `weeks_ago` works analogously for weeks: @@ -3352,35 +3252,7 @@ WARNING: `DateTime` is not aware of DST rules and so some of these methods have NOTE: All the following methods are defined in `active_support/core_ext/date_time/calculations.rb`. -The class `DateTime` is a subclass of `Date` so by loading `active_support/core_ext/date/calculations.rb` you inherit these methods and their aliases, except that they will always return datetimes: - -```ruby -yesterday -tomorrow -beginning_of_week (at_beginning_of_week) -end_of_week (at_end_of_week) -monday -sunday -weeks_ago -prev_week (last_week) -next_week -months_ago -months_since -beginning_of_month (at_beginning_of_month) -end_of_month (at_end_of_month) -prev_month (last_month) -next_month -beginning_of_quarter (at_beginning_of_quarter) -end_of_quarter (at_end_of_quarter) -beginning_of_year (at_beginning_of_year) -end_of_year (at_end_of_year) -years_ago -years_since -prev_year (last_year) -next_year -on_weekday? -on_weekend? -``` +The class `DateTime` is a subclass of `Date` so by loading `active_support/core_ext/date/calculations.rb` you inherit these methods and their aliases, except that they will always return datetimes. The following methods are reimplemented so you do **not** need to load `active_support/core_ext/date/calculations.rb` for these ones: @@ -3528,8 +3400,6 @@ Extensions to `Time` NOTE: All the following methods are defined in `active_support/core_ext/time/calculations.rb`. -Active Support adds to `Time` many of the methods available for `DateTime`: - ```ruby past? today? @@ -3541,6 +3411,8 @@ change advance ago since (in) +prev_day +next_day beginning_of_day (midnight, at_midnight, at_beginning_of_day) end_of_day beginning_of_hour (at_beginning_of_hour) @@ -3556,15 +3428,17 @@ months_ago months_since beginning_of_month (at_beginning_of_month) end_of_month (at_end_of_month) -prev_month (last_month) +prev_month next_month +last_month beginning_of_quarter (at_beginning_of_quarter) end_of_quarter (at_end_of_quarter) beginning_of_year (at_beginning_of_year) end_of_year (at_end_of_year) years_ago years_since -prev_year (last_year) +prev_year +last_year next_year on_weekday? on_weekend? @@ -3622,6 +3496,74 @@ now.all_year # => Fri, 01 Jan 2010 00:00:00 UTC +00:00..Fri, 31 Dec 2010 23:59:59 UTC +00:00 ``` +#### `prev_day`, `next_day` + +In Ruby 1.9 `prev_day` and `next_day` return the date in the last or next day: + +```ruby +d = Date.new(2010, 5, 8) # => Sat, 08 May 2010 +d.prev_day # => Fri, 07 May 2010 +d.next_day # => Sun, 09 May 2010 +``` + +#### `prev_month`, `next_month` + +In Ruby 1.9 `prev_month` and `next_month` return the date with the same day in the last or next month: + +```ruby +d = Date.new(2010, 5, 8) # => Sat, 08 May 2010 +d.prev_month # => Thu, 08 Apr 2010 +d.next_month # => Tue, 08 Jun 2010 +``` + +If such a day does not exist, the last day of the corresponding month is returned: + +```ruby +Date.new(2000, 5, 31).prev_month # => Sun, 30 Apr 2000 +Date.new(2000, 3, 31).prev_month # => Tue, 29 Feb 2000 +Date.new(2000, 5, 31).next_month # => Fri, 30 Jun 2000 +Date.new(2000, 1, 31).next_month # => Tue, 29 Feb 2000 +``` + +#### `prev_year`, `next_year` + +In Ruby 1.9 `prev_year` and `next_year` return a date with the same day/month in the last or next year: + +```ruby +d = Date.new(2010, 5, 8) # => Sat, 08 May 2010 +d.prev_year # => Fri, 08 May 2009 +d.next_year # => Sun, 08 May 2011 +``` + +If date is the 29th of February of a leap year, you obtain the 28th: + +```ruby +d = Date.new(2000, 2, 29) # => Tue, 29 Feb 2000 +d.prev_year # => Sun, 28 Feb 1999 +d.next_year # => Wed, 28 Feb 2001 +``` + +#### `prev_quarter`, `next_quarter` + +`prev_quarter` and `next_quarter` return the date with the same day in the previous or next quarter: + +```ruby +t = Time.local(2010, 5, 8) # => 2010-05-08 00:00:00 +0300 +t.prev_quarter # => 2010-02-08 00:00:00 +0200 +t.next_quarter # => 2010-08-08 00:00:00 +0300 +``` + +If such a day does not exist, the last day of the corresponding month is returned: + +```ruby +Time.local(2000, 7, 31).prev_quarter # => 2000-04-30 00:00:00 +0300 +Time.local(2000, 5, 31).prev_quarter # => 2000-02-29 00:00:00 +0200 +Time.local(2000, 10, 31).prev_quarter # => 2000-07-31 00:00:00 +0300 +Time.local(2000, 11, 31).next_quarter # => 2001-03-01 00:00:00 +0200 +``` + +`prev_quarter` is aliased to `last_quarter`. + ### Time Constructors Active Support defines `Time.current` to be `Time.zone.now` if there's a user time zone defined, with fallback to `Time.now`: |