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| -rw-r--r-- | ChangeLog | 5 | ||||
| -rw-r--r-- | doc/syntax/modules_and_classes.rdoc | 45 |
2 files changed, 50 insertions, 0 deletions
@@ -1,3 +1,8 @@ +Sun Jan 6 05:35:18 2013 Eric Hodel <drbrain@segment7.net> + + * doc/syntax/modules_and_classes.rdoc: Added singleton classes + documentation. + Sun Jan 6 02:22:00 2013 Zachary Scott <zachary@zacharyscott.net> * lib/webrick/httpservlet/abstract.rb (WEBrick::HTTPServlet): Typo in diff --git a/doc/syntax/modules_and_classes.rdoc b/doc/syntax/modules_and_classes.rdoc index cca9dc2563..65bd31bf7d 100644 --- a/doc/syntax/modules_and_classes.rdoc +++ b/doc/syntax/modules_and_classes.rdoc @@ -291,3 +291,48 @@ provide them manually like <code>super(2)</code>. +super+ may be called as many times as you like in the subclass method. += Singleton Classes + +The singleton class (also known as the metaclass or eigenclass) of an object is +a class that holds methods for only that instance. You can access the +singleton class of an object using <code>class << object</code> like this: + + class C + end + + class << C + # self is the singleton class here + end + +Most frequently you'll see the singleton class accessed like this: + + class C + class << self + # ... + end + end + +This allows definition of methods and attributes on a class (or module) without +needing to write <code>def self.my_method</code>. + +Since you can open the singleton class of any object this means that this code +block: + + o = Object.new + + def o.my_method + 1 + 1 + end + +is equivalent to this code block: + + o = Object.new + + class << o + def my_method + 1 + 1 + end + end + +Both objects with have a +my_method+ that returns +2+. + |