diff --git a/include/xo/object2/DArray.hpp b/include/xo/object2/DArray.hpp
index 879bb76c..55d5e068 100644
--- a/include/xo/object2/DArray.hpp
+++ b/include/xo/object2/DArray.hpp
@@ -5,8 +5,8 @@
 
 #pragma once
 
-#include <xo/gc/GCObject.hpp>
-#include <xo/gc/Collector.hpp>
+#include <xo/alloc2/GCObject.hpp>
+#include <xo/alloc2/Collector.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
diff --git a/include/xo/object2/DBoolean.hpp b/include/xo/object2/DBoolean.hpp
index 69dd1c16..ee9fe3be 100644
--- a/include/xo/object2/DBoolean.hpp
+++ b/include/xo/object2/DBoolean.hpp
@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include <xo/gc/Collector.hpp>
+#include <xo/alloc2/Collector.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
 #include <xo/facet/obj.hpp>
diff --git a/include/xo/object2/DDictionary.hpp b/include/xo/object2/DDictionary.hpp
index 1f028434..f5844088 100644
--- a/include/xo/object2/DDictionary.hpp
+++ b/include/xo/object2/DDictionary.hpp
@@ -7,8 +7,8 @@
 
 #include "DArray.hpp"
 #include "DString.hpp"
-#include <xo/gc/GCObject.hpp>
-#include <xo/gc/Collector.hpp>
+#include <xo/alloc2/GCObject.hpp>
+#include <xo/alloc2/Collector.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
diff --git a/include/xo/object2/DFloat.hpp b/include/xo/object2/DFloat.hpp
index a46a990d..4e4be861 100644
--- a/include/xo/object2/DFloat.hpp
+++ b/include/xo/object2/DFloat.hpp
@@ -6,7 +6,7 @@
 #pragma once
 
 #include <xo/alloc2/Allocator.hpp>
-#include <xo/gc/Collector.hpp>
+#include <xo/alloc2/Collector.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
 
diff --git a/include/xo/object2/DInteger.hpp b/include/xo/object2/DInteger.hpp
index b03693be..3fd13672 100644
--- a/include/xo/object2/DInteger.hpp
+++ b/include/xo/object2/DInteger.hpp
@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include <xo/gc/Collector.hpp>
+#include <xo/alloc2/Collector.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
 #include <xo/facet/obj.hpp>
diff --git a/include/xo/object2/DList.hpp b/include/xo/object2/DList.hpp
index 39e0b584..50ab8dd7 100644
--- a/include/xo/object2/DList.hpp
+++ b/include/xo/object2/DList.hpp
@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include <xo/gc/GCObject.hpp>
+#include <xo/alloc2/GCObject.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
 
diff --git a/include/xo/object2/DString.hpp b/include/xo/object2/DString.hpp
index a6cedb00..bb57e3da 100644
--- a/include/xo/object2/DString.hpp
+++ b/include/xo/object2/DString.hpp
@@ -6,7 +6,7 @@
 #pragma once
 
 #include <xo/alloc2/Allocator.hpp>
-#include <xo/gc/Collector.hpp>
+#include <xo/alloc2/Collector.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/indentlog/print/ppindentinfo.hpp>
 #include <string_view>
@@ -15,6 +15,8 @@
 //#include <cstdio>
 
 namespace xo {
+    namespace mm { class ACollector; }
+
     namespace scm {
         /** @class DString
          *  @brief String implementation with gc hooks
@@ -111,14 +113,7 @@ namespace xo {
             static DString * printf(obj<AAllocator> mm,
                                     size_type cap,
                                     const char * fmt,
-                                    Args&&... args)
-            {
-                DString * result = DString::empty(mm, cap);
-                if (result) {
-                    result->sprintf(fmt, std::forward<Args>(args)...);
-                }
-                return result;
-            }
+                                    Args&&... args);
 
             ///@}
             /** @defgroup dstring-access access methods **/
@@ -252,8 +247,10 @@ namespace xo {
             /** clone string, using memory from allocator @p mm **/
             DString * shallow_copy(obj<AAllocator> mm) const noexcept;
 
-            /** fixup child pointers (trivial for DString, no children) **/
             size_type forward_children(obj<ACollector> gc) noexcept;
+            /** fixup child pointers (trivial for DString, no children)
+             *  note: cref so we can use forward decl
+             **/
 
             ///@}
 
@@ -285,6 +282,24 @@ namespace xo {
             ///@}
         };
 
+        /** create string using printf-style formatting.
+         *  Use memory from allocator @p mm with capacity @p cap.
+         *  Truncates if result exceeds capacity.
+         *  @return pointer to newly created DString
+         **/
+        template <typename... Args>
+        DString * DString::printf(obj<AAllocator> mm,
+                                  size_type cap,
+                                  const char * fmt,
+                                  Args&&... args)
+        {
+            DString * result = DString::empty(mm, cap);
+            if (result) {
+                result->sprintf(fmt, std::forward<Args>(args)...);
+            }
+            return result;
+        }
+
         inline std::ostream & operator<<(std::ostream & os, const DString * x) {
             if (x) {
                 os << std::string_view(*x);
diff --git a/include/xo/object2/String.hpp b/include/xo/object2/String.hpp
index 111b04fb..f3d0527b 100644
--- a/include/xo/object2/String.hpp
+++ b/include/xo/object2/String.hpp
@@ -9,4 +9,6 @@
 #include "string/IGCObject_DString.hpp"
 #include "string/IPrintable_DString.hpp"
 
+#include <xo/alloc2/Allocator.hpp>
+
 /* end String.hpp */
diff --git a/include/xo/object2/array/IGCObject_DArray.hpp b/include/xo/object2/array/IGCObject_DArray.hpp
index 9af6d3c7..08f78aa8 100644
--- a/include/xo/object2/array/IGCObject_DArray.hpp
+++ b/include/xo/object2/array/IGCObject_DArray.hpp
@@ -14,7 +14,7 @@
 #pragma once
 
 #include "GCObject.hpp"
-#include <xo/gc/GCObject.hpp>
+#include <xo/alloc2/GCObject.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include "DArray.hpp"
 
@@ -64,4 +64,4 @@ namespace xo {
     } /*namespace scm*/
 } /*namespace xo*/
 
-/* end */
\ No newline at end of file
+/* end */
diff --git a/include/xo/object2/boolean/IGCObject_DBoolean.hpp b/include/xo/object2/boolean/IGCObject_DBoolean.hpp
index 1d90b60e..358aad18 100644
--- a/include/xo/object2/boolean/IGCObject_DBoolean.hpp
+++ b/include/xo/object2/boolean/IGCObject_DBoolean.hpp
@@ -14,7 +14,7 @@
 #pragma once
 
 #include "GCObject.hpp"
-#include <xo/gc/GCObject.hpp>
+#include <xo/alloc2/GCObject.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include "DBoolean.hpp"
 
@@ -64,4 +64,4 @@ namespace xo {
     } /*namespace scm*/
 } /*namespace xo*/
 
-/* end */
\ No newline at end of file
+/* end */
diff --git a/include/xo/object2/dictionary/IGCObject_DDictionary.hpp b/include/xo/object2/dictionary/IGCObject_DDictionary.hpp
index 7f2e0ad9..7fe1bc55 100644
--- a/include/xo/object2/dictionary/IGCObject_DDictionary.hpp
+++ b/include/xo/object2/dictionary/IGCObject_DDictionary.hpp
@@ -14,7 +14,7 @@
 #pragma once
 
 #include "GCObject.hpp"
-#include <xo/gc/GCObject.hpp>
+#include <xo/alloc2/GCObject.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include "DDictionary.hpp"
 
@@ -64,4 +64,4 @@ namespace xo {
     } /*namespace scm*/
 } /*namespace xo*/
 
-/* end */
\ No newline at end of file
+/* end */
diff --git a/include/xo/object2/number/IGCObject_DFloat.hpp b/include/xo/object2/number/IGCObject_DFloat.hpp
index 9a1dcbdc..b8e15b73 100644
--- a/include/xo/object2/number/IGCObject_DFloat.hpp
+++ b/include/xo/object2/number/IGCObject_DFloat.hpp
@@ -15,7 +15,7 @@
 
 #include "GCObject.hpp"
 #include <xo/object2/number/GCObjectConversion_DFloat.hpp>
-#include <xo/gc/GCObject.hpp>
+#include <xo/alloc2/GCObject.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include "DFloat.hpp"
 
@@ -65,4 +65,4 @@ namespace xo {
     } /*namespace scm*/
 } /*namespace xo*/
 
-/* end */
\ No newline at end of file
+/* end */
diff --git a/include/xo/object2/number/IGCObject_DInteger.hpp b/include/xo/object2/number/IGCObject_DInteger.hpp
index 1136b577..fd2ea642 100644
--- a/include/xo/object2/number/IGCObject_DInteger.hpp
+++ b/include/xo/object2/number/IGCObject_DInteger.hpp
@@ -14,7 +14,7 @@
 #pragma once
 
 #include "GCObject.hpp"
-#include <xo/gc/GCObject.hpp>
+#include <xo/alloc2/GCObject.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include "DInteger.hpp"
 
@@ -64,4 +64,4 @@ namespace xo {
     } /*namespace scm*/
 } /*namespace xo*/
 
-/* end */
\ No newline at end of file
+/* end */
diff --git a/include/xo/object2/object2_register_facets.hpp b/include/xo/object2/object2_register_facets.hpp
index e419b794..7f42d5a0 100644
--- a/include/xo/object2/object2_register_facets.hpp
+++ b/include/xo/object2/object2_register_facets.hpp
@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include <xo/gc/Collector.hpp>
+#include <xo/alloc2/Collector.hpp>
 
 namespace xo {
     namespace scm {
diff --git a/include/xo/object2/object2_register_types.hpp b/include/xo/object2/object2_register_types.hpp
index 5c61692d..5663b086 100644
--- a/include/xo/object2/object2_register_types.hpp
+++ b/include/xo/object2/object2_register_types.hpp
@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include <xo/gc/Collector.hpp>
+#include <xo/alloc2/Collector.hpp>
 
 namespace xo {
     namespace scm {
diff --git a/include/xo/object2/sequence/ASequence.hpp b/include/xo/object2/sequence/ASequence.hpp
index 53d112e7..44f1d1cb 100644
--- a/include/xo/object2/sequence/ASequence.hpp
+++ b/include/xo/object2/sequence/ASequence.hpp
@@ -14,7 +14,7 @@
 #pragma once
 
 // includes (via {facet_includes})
-#include <xo/gc/GCObject.hpp>
+#include <xo/alloc2/GCObject.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/facet/facet_implementation.hpp>
 #include <xo/facet/typeseq.hpp>
diff --git a/include/xo/object2/sequence/ISequence_Xfer.hpp b/include/xo/object2/sequence/ISequence_Xfer.hpp
index 42d6cb1b..e0511e41 100644
--- a/include/xo/object2/sequence/ISequence_Xfer.hpp
+++ b/include/xo/object2/sequence/ISequence_Xfer.hpp
@@ -13,7 +13,7 @@
 
 #pragma once
 
-#include <xo/gc/GCObject.hpp>
+#include <xo/alloc2/GCObject.hpp>
 
 namespace xo {
 namespace scm {
diff --git a/include/xo/object2/string/IGCObject_DString.hpp b/include/xo/object2/string/IGCObject_DString.hpp
index 159b9e49..2a907f37 100644
--- a/include/xo/object2/string/IGCObject_DString.hpp
+++ b/include/xo/object2/string/IGCObject_DString.hpp
@@ -14,7 +14,7 @@
 #pragma once
 
 #include "GCObject.hpp"
-#include <xo/gc/GCObject.hpp>
+#include <xo/alloc2/GCObject.hpp>
 #include <xo/alloc2/Allocator.hpp>
 #include "DString.hpp"
 
@@ -64,4 +64,4 @@ namespace xo {
     } /*namespace scm*/
 } /*namespace xo*/
 
-/* end */
\ No newline at end of file
+/* end */
diff --git a/src/object2/DList.cpp b/src/object2/DList.cpp
index 01d01d61..25770d01 100644
--- a/src/object2/DList.cpp
+++ b/src/object2/DList.cpp
@@ -6,7 +6,7 @@
 #include "DList.hpp"
 #include "list/IPrintable_DList.hpp"
 #include "list/IGCObject_DList.hpp"
-#include <xo/gc/GCObject.hpp>
+#include <xo/alloc2/GCObject.hpp>
 #include <xo/printable2/Printable.hpp>
 #include <xo/facet/FacetRegistry.hpp>
 #include <xo/facet/facet_implementation.hpp>
diff --git a/src/object2/DString.cpp b/src/object2/DString.cpp
index 69baa5d6..230fa4a4 100644
--- a/src/object2/DString.cpp
+++ b/src/object2/DString.cpp
@@ -4,12 +4,13 @@
  **/
 
 #include "DString.hpp"
+#include <xo/alloc2/Allocator.hpp>
 #include <xo/indentlog/print/pretty.hpp>
 #include <algorithm>
 #include <cstring>
 
 namespace xo {
-    using xo::facet::typeseq;
+    using xo::reflect::typeseq;
     using xo::print::ppdetail_atomic;
 
     namespace scm {
diff --git a/utest/DString.test.cpp b/utest/DString.test.cpp
index 39dffef5..53db8e7f 100644
--- a/utest/DString.test.cpp
+++ b/utest/DString.test.cpp
@@ -5,6 +5,7 @@
 
 #include "init_object2.hpp"
 #include "StringOps.hpp"
+#include <xo/alloc2/Allocator.hpp>
 #include <xo/alloc2/arena/IAllocator_DArena.hpp>
 #include <catch2/catch.hpp>
 #include <cctype>
diff --git a/utest/Printable.test.cpp b/utest/Printable.test.cpp
index 64736d22..2ca792fa 100644
--- a/utest/Printable.test.cpp
+++ b/utest/Printable.test.cpp
@@ -19,7 +19,7 @@
 #include <xo/object2/DInteger.hpp>
 #include <xo/object2/number/IGCObject_DInteger.hpp>
 
-#include <xo/gc/Collector.hpp>
+#include <xo/alloc2/Collector.hpp>
 #include <xo/gc/DX1Collector.hpp>
 #include <xo/gc/detail/IAllocator_DX1Collector.hpp>
 #include <xo/gc/detail/ICollector_DX1Collector.hpp>
diff --git a/utest/X1Collector.test.cpp b/utest/X1Collector.test.cpp
index 90122c25..a2a2dec5 100644
--- a/utest/X1Collector.test.cpp
+++ b/utest/X1Collector.test.cpp
@@ -16,7 +16,7 @@
 #include "list/IGCObject_DList.hpp"
 
 #include <xo/gc/CollectorTypeRegistry.hpp>
-#include <xo/gc/Collector.hpp>
+#include <xo/alloc2/Collector.hpp>
 #include <xo/gc/DX1Collector.hpp>
 
 #include <xo/gc/detail/IAllocator_DX1Collector.hpp>