xo-objectd2 xo-printable xo-facet: pp working for List(Integer)

Also streamline facet switching

include/xo/object2/DInteger.hpp

@@ -5,11 +5,32 @@
 
 #pragma once
 
+#include <xo/alloc2/Allocator.hpp>
+#include <xo/indentlog/print/ppindentinfo.hpp>
 #include <cstdint>
 
 namespace xo {
     namespace scm {
-        using DInteger = std::int64_t;
+        struct DInteger {
+            using AAllocator = xo::mm::AAllocator;
+            using ppindentinfo = xo::print::ppindentinfo;
+
+            explicit DInteger(long x) : value_{x} {}
+
+            /** allocate boxed value @p x using memory from @p mm **/
+            static DInteger * make(obj<AAllocator> mm,
+                                   long x);
+
+            double value() const noexcept { return value_; }
+
+            bool pretty(const ppindentinfo & ppii) const;
+
+            operator long() const noexcept { return value_; }
+
+        private:
+            /** boxed integer value **/
+            long value_;
+        };
     } /*nmaespace obj*/
 } /*namespace xo*/