method

clone

v1_8_7_72 - Show latest stable - 1 note - Class: Object

clone() public

Produces a shallow copy of obj—the instance variables of obj are copied, but not the objects they reference. Copies the frozen and tainted state of obj. See also the discussion under Object#dup.

   class Klass
      attr_accessor :str
   end
   s1 = Klass.new      #=> #<Klass:0x401b3a38>
   s1.str = "Hello"    #=> "Hello"
   s2 = s1.clone       #=> #<Klass:0x401b3998 @str="Hello">
   s2.str[1,4] = "i"   #=> "i"
   s1.inspect          #=> "#<Klass:0x401b3a38 @str=\"Hi\">"
   s2.inspect          #=> "#<Klass:0x401b3998 @str=\"Hi\">"

This method may have class-specific behavior. If so, that behavior will be documented under the #initialize_copy method of the class.

Show source

/*
 *  call-seq:
 *     obj.clone -> an_object
 *  
 *  Produces a shallow copy of <i>obj</i>---the instance variables of
 *  <i>obj</i> are copied, but not the objects they reference. Copies
 *  the frozen and tainted state of <i>obj</i>. See also the discussion
 *  under <code>Object#dup</code>.
 *     
 *     class Klass
 *        attr_accessor :str
 *     end
 *     s1 = Klass.new      #=> #<Klass:0x401b3a38>
 *     s1.str = "Hello"    #=> "Hello"
 *     s2 = s1.clone       #=> #<Klass:0x401b3998 @str="Hello">
 *     s2.str[1,4] = "i"   #=> "i"
 *     s1.inspect          #=> "#<Klass:0x401b3a38 @str=\"Hi\">"
 *     s2.inspect          #=> "#<Klass:0x401b3998 @str=\"Hi\">"
 *
 *  This method may have class-specific behavior.  If so, that
 *  behavior will be documented under the #+initialize_copy+ method of
 *  the class.
 */

VALUE
rb_obj_clone(obj)
    VALUE obj;
{
    VALUE clone;

    if (rb_special_const_p(obj)) {
        rb_raise(rb_eTypeError, "can't clone %s", rb_obj_classname(obj));
    }
    clone = rb_obj_alloc(rb_obj_class(obj));
    RBASIC(clone)->klass = rb_singleton_class_clone(obj);
    RBASIC(clone)->flags = (RBASIC(obj)->flags | FL_TEST(clone, FL_TAINT)) & ~(FL_FREEZE|FL_FINALIZE);
    init_copy(clone, obj);
    RBASIC(clone)->flags |= RBASIC(obj)->flags & FL_FREEZE;

    return clone;
}

November 16, 2011

1 thank

Change in clone for ActiveRecord objects in ruby-1.9.3

I noticed that cloning an active record object in ruby-1.9.3 and then changing an attribute on the original object will actually change the cloned object as well. This was not the case in ruby-1.9.2.

clone

Related methods

Change in clone for ActiveRecord objects in ruby-1.9.3