Bug #3016: Enumerable#slice_before and dup
http://redmine.ruby-lang.org/issues/show/3016

Author: Marc-Andre Lafortune
Status: Open, Priority: Low
Category: core, Target version: 1.9.2
ruby -v: ruby 1.9.2dev (2010-03-03 trunk 26805) [x86_64-darwin10.2.0]

When writing the specs for slice_before, I was surprised that it doesn't call #dup.

class X
  def dup
    raise "Hi!"
  end
end

[:foo].slice_before(X.new){}.to_a
  # ==> [[:foo]], I expected it to raise

The implementation calls directly rb_obj_dup.

It's a minor issue, but would it not be best to call dup on the argument? Most special needs for #dup can be addressed by initialize_dup, but maybe there are some reasonable cases where some user classes will redefine #dup?

The same question is valid for Enumerable#chunk.


diff --git a/enum.c b/enum.c
index b69d8c9..e6e6adb 100644
--- a/enum.c
+++ b/enum.c
@@ -14,7 +14,7 @@
 #include "node.h"
 
 VALUE rb_mEnumerable;
-static ID id_each, id_eqq, id_cmp, id_next, id_size;
+static ID id_each, id_eqq, id_cmp, id_next, id_size, id_dup;
 
 static VALUE
 enum_values_pack(int argc, VALUE *argv)
@@ -2189,7 +2189,7 @@ chunk_i(VALUE yielder, VALUE enumerator, int argc, VALUE *argv)
     arg.yielder = yielder;
 
     if (!NIL_P(arg.state))
-        arg.state = rb_obj_dup(arg.state);
+        arg.state = rb_funcall(arg.state, id_dup, 0, 0);
 
     rb_block_call(enumerable, id_each, 0, 0, chunk_ii, (VALUE)&arg);
     if (!NIL_P(arg.prev_elts))
@@ -2364,7 +2364,7 @@ slicebefore_i(VALUE yielder, VALUE enumerator, int argc, VALUE *argv)
     arg.yielder = yielder;
 
     if (!NIL_P(arg.state))
-        arg.state = rb_obj_dup(arg.state);
+        arg.state = rb_funcall(arg.state, id_dup, 0, 0);
 
     rb_block_call(enumerable, id_each, 0, 0, slicebefore_ii, (VALUE)&arg);
     if (!NIL_P(arg.prev_elts))
@@ -2606,5 +2606,6 @@ Init_Enumerable(void)
     id_cmp  = rb_intern("<=>");
     id_next = rb_intern("next");
     id_size = rb_intern("size");
+    id_dup  = rb_intern("dup");
 }


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