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instance method · added in Ruby 3.2

Class#attached_object

attached_object → object

VALUE
rb_class_attached_object(VALUE klass)
{
    if (!FL_TEST(klass, FL_SINGLETON)) {
        rb_raise(rb_eTypeError, "`%"PRIsVALUE"' is not a singleton class", klass);
    }

    return rb_attr_get(klass, id_attached);
}

Returns the object for which the receiver is the singleton class.

Raises an TypeError if the class is not a singleton class.

Example

class Foo; end

Foo.singleton_class.attached_object        #=> Foo
Foo.attached_object                        #=> TypeError: `Foo' is not a singleton class
Foo.new.singleton_class.attached_object    #=> #<Foo:0x000000010491a370>
TrueClass.attached_object                  #=> TypeError: `TrueClass' is not a singleton class
NilClass.attached_object                   #=> TypeError: `NilClass' is not a singleton class

Ruby version changes

3.2

Class#attached_object, which returns the object for which the receiver is the singleton class. Raises TypeError if the receiver is not a singleton class. [Feature #12084]

Example

class Foo; end

Foo.singleton_class.attached_object        #=> Foo
Foo.new.singleton_class.attached_object    #=> #<Foo:0x000000010491a370>
Foo.attached_object                        #=> TypeError: `Foo' is not a singleton class
nil.singleton_class.attached_object        #=> TypeError: `NilClass' is not a singleton class

See also #allocate #inherited .new #json_creatable? also in 4.1 · 4.0 · 3.4 · 3.3

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