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author | José Valim <jose.valim@gmail.com> | 2010-07-05 12:50:08 +0200 |
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committer | José Valim <jose.valim@gmail.com> | 2010-07-05 13:01:27 +0200 |
commit | a5dda97602f2188a13cbcab5c7e9a5ba84ba876b (patch) | |
tree | be84ca4360059f6eb3f696b46e1bdad3d57b1ce2 /railties | |
parent | 5bf3294c8b3aeb3afd426e8c182456c675829c1e (diff) | |
download | rails-a5dda97602f2188a13cbcab5c7e9a5ba84ba876b.tar.gz rails-a5dda97602f2188a13cbcab5c7e9a5ba84ba876b.tar.bz2 rails-a5dda97602f2188a13cbcab5c7e9a5ba84ba876b.zip |
Define a convention for descendants and subclasses.
The former should be symmetric with ancestors and include all children. However, it should not include self since ancestors + descendants should not have duplicated. The latter is symmetric to superclass in the sense it only includes direct children.
By adopting a convention, we expect to have less conflict with other frameworks, as Datamapper. For this moment, to ensure ActiveModel::Validations can be used with Datamapper, we should always call ActiveSupport::DescendantsTracker.descendants(self) internally instead of self.descendants avoiding conflicts.
Diffstat (limited to 'railties')
-rw-r--r-- | railties/guides/source/active_support_core_extensions.textile | 81 |
1 files changed, 29 insertions, 52 deletions
diff --git a/railties/guides/source/active_support_core_extensions.textile b/railties/guides/source/active_support_core_extensions.textile index 844b9428bd..de0c00ac68 100644 --- a/railties/guides/source/active_support_core_extensions.textile +++ b/railties/guides/source/active_support_core_extensions.textile @@ -387,40 +387,6 @@ TIP: Since +with_options+ forwards calls to its receiver they can be nested. Eac NOTE: Defined in +active_support/core_ext/object/with_options.rb+. -h5. +subclasses_of+ - -The method +subclasses_of+ receives an arbitrary number of class objects and returns all their anonymous or reachable descendants as a single array: - -<ruby> -class C; end -subclasses_of(C) # => [] - -subclasses_of(Integer) # => [Bignum, Fixnum] - -module M - class A; end - class B1 < A; end - class B2 < A; end -end - -module N - class C < M::B1; end -end - -subclasses_of(M::A) # => [N::C, M::B2, M::B1] -</ruby> - -The order in which these classes are returned is unspecified. The returned collection may have duplicates: - -<ruby> -subclasses_of(Numeric, Integer) -# => [Bignum, Float, Fixnum, Integer, Date::Infinity, Rational, BigDecimal, Bignum, Fixnum] -</ruby> - -See also +Class#subclasses+ in "Extensions to +Class+ FIX THIS LINK":FIXME. - -NOTE: Defined in +active_support/core_ext/object/extending.rb+. - h4. Instance Variables Active Support provides several methods to ease access to instance variables. @@ -1141,36 +1107,47 @@ If for whatever reason an application loads the definition of a mailer class and NOTE: Defined in +active_support/core_ext/class/delegating_attributes.rb+. -h4. Descendants +h4. Descendants & Subclasses -h5. +subclasses+ +h5. +descendants+ -The +subclasses+ method returns the names of all the anonymous or reachable descendants of its receiver as an array of strings: +The +descendants+ method returns all classes, including its children, that inherits from self. <ruby> class C; end -C.subclasses # => [] - -Integer.subclasses # => ["Bignum", "Fixnum"] +C.descendants #=> [] -module M - class A; end - class B1 < A; end - class B2 < A; end -end +class B < C; end +C.descendants #=> [B] -module N - class C < M::B1; end -end +class A < B; end +C.descendants #=> [B, A] -M::A.subclasses # => ["N::C", "M::B2", "M::B1"] +class D < C; end +C.descendants #=> [B, A, D] </ruby> -The order in which these class names are returned is unspecified. +h5. +subclasses+ + +The +subclasses+ method returns all direct classes that inherits from self. + +<ruby> +class C; end +C.subclasses #=> [] + +class B < C; end +C.subclasses #=> [B] + +class A < B; end +C.subclasses #=> [B] + +class D < C; end +C.subclasses #=> [B, D] +</ruby> -See also +Object#subclasses_of+ in "Extensions to All Objects FIX THIS LINK":FIXME. +The order in which these class are returned is unspecified. -WARNING: This method is redefined in some Rails core classes. +WARNING: This method is redefined in some Rails core classes but should be all compatible in Rails 3.1. NOTE: Defined in +active_support/core_ext/class/subclasses.rb+. |