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| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | object.c | 39 |
2 files changed, 39 insertions, 7 deletions
@@ -1,3 +1,10 @@ +Thu Nov 21 14:18:24 2013 Zachary Scott <e@zzak.io> + + * object.c: [DOC] Clarify Object#dup vs #clone [Bug #9128] + Moving existing doc for this comparison to separate section of #dup + Adding examples to document behavior of #dup with Module#extend. + Based on a patch by stevegoobermanhill + Thu Nov 21 14:06:02 2013 Koichi Sasada <ko1@atdot.net> * gc.c (gc_marks_check): do not dump all refs. @@ -356,17 +356,42 @@ rb_obj_clone(VALUE obj) * obj.dup -> 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. - * <code>dup</code> copies the tainted state of <i>obj</i>. See also - * the discussion under <code>Object#clone</code>. In general, - * <code>clone</code> and <code>dup</code> may have different semantics - * in descendant classes. While <code>clone</code> is used to duplicate - * an object, including its internal state, <code>dup</code> typically - * uses the class of the descendant object to create the new instance. + * <i>obj</i> are copied, but not the objects they reference. <code>dup</code> + * copies the tainted state of <i>obj</i>. * * This method may have class-specific behavior. If so, that * behavior will be documented under the #+initialize_copy+ method of * the class. + * + * === on dup vs clone + * + * In general, <code>clone</code> and <code>dup</code> may have different + * semantics in descendant classes. While <code>clone</code> is used to + * duplicate an object, including its internal state, <code>dup</code> + * typically uses the class of the descendant object to create the new + * instance. + * + * When using #dup any modules that the object has been extended with will not + * be copied. + * + * class Klass + * attr_accessor :str + * end + * + * module Foo + * def foo; 'foo'; end + * end + * + * s1 = Klass.new #=> #<Klass:0x401b3a38> + * s1.extend(Foo) #=> #<Klass:0x401b3a38> + * s1.foo #=> "foo" + * + * s2 = s1.clone #=> #<Klass:0x401b3a38> + * s2.foo #=> "foo" + * + * s3 = s1.dup #=> #<Klass:0x401b3a38> + * s3.foo #=> NoMethodError: undefined method `foo' for #<Klass:0x401b3a38> + * */ VALUE |