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| -rw-r--r-- | railties/guides/source/active_support_core_extensions.textile | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/railties/guides/source/active_support_core_extensions.textile b/railties/guides/source/active_support_core_extensions.textile index 3890341d13..7af89a6d24 100644 --- a/railties/guides/source/active_support_core_extensions.textile +++ b/railties/guides/source/active_support_core_extensions.textile @@ -849,6 +849,44 @@ The method receives the name of an action, and a +:with+ option with code. The c NOTE: Defined in +active_support/core_ext/module/synchronization.rb+. +h4. Reachable Modules + +A named module is reachable if it is stored in its correspoding 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 +</ruby> + +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 +</ruby> + +NOTE: Defined in +active_support/core_ext/module/reachable.rb+. + h3. Extensions to +Class+ h4. Class Attributes |