instance method

BasicObject#id

() -> ::Integer

obj.__id__ → integer

obj.object_id → integer

VALUE
rb_obj_id(VALUE obj)
{
    /* If obj is an immediate, the object ID is obj directly converted to a Numeric.
     * Otherwise, the object ID is a Numeric that is a non-zero multiple of
     * (RUBY_IMMEDIATE_MASK + 1) which guarantees that it does not collide with
     * any immediates. */
    return rb_find_object_id(rb_gc_get_objspace(), obj, object_id);
}

Returns an integer identifier for obj.

The same number will be returned on all calls to object_id for a given object, and no two active objects will share an id.

Note: that some objects of builtin classes are reused for optimization. This is the case for immediate values and frozen string literals.

BasicObject implements __id__, Kernel implements object_id.

Immediate values are not passed by reference but are passed by value: nil, true, false, Fixnums, Symbols, and some Floats.

Example

Object.new.object_id  == Object.new.object_id  # => false
(21 * 2).object_id    == (21 * 2).object_id    # => true
"hello".object_id     == "hello".object_id     # => false
"hi".freeze.object_id == "hi".freeze.object_id # => true

See also #equal? #instance_eval #== #instance_exec also in 4.1 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0

‹ prev#equal? next ›#instance_eval

BasicObject#__id__

BasicObject#id