Merge pull request #177 from quantopian/sequence-to-object

ENH: Create sequence_to_object

Author: gerrymanoim

include/libpy/to_object.h

@@ -67,25 +67,28 @@ py::owned_ref<> to_object(T&& ob) {
 }
 
 namespace dispatch {
-template<typename C>
-py::owned_ref<> sequence_to_list(const C& v) {
-    py::owned_ref out(PyList_New(v.size()));
-    if (!out) {
-        return nullptr;
-    }
 
-    std::size_t ix = 0;
-    for (const auto& elem : v) {
-        PyObject* ob = py::to_object(elem).escape();
-        if (!ob) {
+template<typename C>
+struct sequence_to_object {
+    static py::owned_ref<> f(const C& v) {
+        py::owned_ref out(PyList_New(v.size()));
+        if (!out) {
             return nullptr;
         }
 
-        PyList_SET_ITEM(out.get(), ix++, ob);
-    }
+        std::size_t ix = 0;
+        for (const auto& elem : v) {
+            PyObject* ob = py::to_object(elem).escape();
+            if (!ob) {
+                return nullptr;
+            }
 
-    return out;
-}
+            PyList_SET_ITEM(out.get(), ix++, ob);
+        }
+
+        return out;
+    }
+};
 
 template<std::size_t n>
 struct to_object<std::array<char, n>> {
@@ -102,11 +105,7 @@ struct to_object<char> {
 };
 
 template<typename T, std::size_t n>
-struct to_object<std::array<T, n>> {
-    static py::owned_ref<> f(const std::array<T, n>& v) {
-        return sequence_to_list(v);
-    }
-};
+struct to_object<std::array<T, n>> : public sequence_to_object<std::array<T, n>> {};
 
 /** Identity conversion for `owned_ref`.
  */
@@ -273,11 +272,7 @@ struct to_object<std::unordered_map<K, V, Hash, KeyEqual>>
     : public map_to_object<std::unordered_map<K, V, Hash, KeyEqual>> {};
 
 template<typename T>
-struct to_object<std::vector<T>> {
-    static py::owned_ref<> f(const std::vector<T>& v) {
-        return sequence_to_list(v);
-    }
-};
+struct to_object<std::vector<T>> : public sequence_to_object<std::vector<T>> {};
 
 template<typename S>
 struct set_to_object {