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instance method · added in Ruby 3.2

Class#attached_object

() -> untyped

attached_object → object

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

    const VALUE obj = RCLASS_ATTACHED_OBJECT(klass);

    /* A singleton class is shareable whatever it is attached to, so another Ractor can
     * hold one attached to an unshareable object.  Returning it would share it. */
    if (rb_objspace_foreign_object_p(obj) && !RB_OBJ_SHAREABLE_P(obj)) {
        /* No klass in the message: naming a singleton class inspects the very object we
         * must not touch from here. */
        rb_raise(rb_eRactorIsolationError,
                 "can not get an unshareable attached object from another Ractor");
    }

    return obj;
}

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

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

Raises a Ractor::IsolationError if the attached object is not shareable and belongs to another Ractor.

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 #new also in 4.0 · 3.4 · 3.3 · 3.2

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