Simplifications in tuple and vector converter, Improve error messages

Author: Wentzell

c++/cpp2py/converters/tuple.hpp

@@ -15,45 +15,48 @@ namespace cpp2py {
     // c2py implementation
     template <typename T, auto... Is> static PyObject *c2py_impl(T &&t, std::index_sequence<Is...>) {
       auto objs        = std::array<pyref, sizeof...(Is)>{convert_to_python(std::get<Is>(std::forward<T>(t)))...};
-      bool one_is_null = std::accumulate(std::begin(objs), std::end(objs), false, [](bool x, PyObject *a) { return x or (a == NULL); });
+      bool one_is_null = std::any_of(std::begin(objs), std::end(objs), [](PyObject *a) { return a == NULL; });
       if (one_is_null) return NULL;
       return PyTuple_Pack(sizeof...(Types), (PyObject *)(objs[Is])...);
     }
 
-    // is_convertible implementation
-    template <auto... Is> static bool is_convertible_impl(PyObject *seq, bool raise_exception, std::index_sequence<Is...>) {
-      return (py_converter<std::decay_t<Types>>::is_convertible(PySequence_Fast_GET_ITEM(seq, Is), raise_exception) and ...);
-    }
-
-    template <auto... Is> static auto py2c_impl(PyObject *seq, std::index_sequence<Is...>) {
-      return std::make_tuple(py_converter<std::decay_t<Types>>::py2c(PySequence_Fast_GET_ITEM(seq, Is))...);
-    }
-
     public:
-    // -----------------------------------------
-
     template <typename T> static PyObject *c2py(T &&t) {
       static_assert(is_instantiation_of_v<std::tuple, std::decay_t<T>>, "Logic Error");
       return c2py_impl(std::forward<T>(t), std::make_index_sequence<sizeof...(Types)>());
     }
 
     // -----------------------------------------
 
+    private:
+    // is_convertible implementation
+    template <auto... Is> static bool is_convertible_impl(PyObject *seq, bool raise_exception, std::index_sequence<Is...>) {
+      return (py_converter<std::decay_t<Types>>::is_convertible(PySequence_Fast_GET_ITEM(seq, Is), raise_exception) and ...);
+    }
+
+    public:
     static bool is_convertible(PyObject *ob, bool raise_exception) {
-      if (PySequence_Check(ob)) {
-        pyref seq = PySequence_Fast(ob, "expected a sequence");
-        // Sizes must match! Could we relax this condition to '<'?
-        if (PySequence_Fast_GET_SIZE((PyObject *)seq) != std::tuple_size<tuple_t>::value) goto _false;
-        if (!is_convertible_impl((PyObject *)seq, raise_exception, std::make_index_sequence<sizeof...(Types)>())) goto _false;
-        return true;
+      if (not PySequence_Check(ob)) {
+        if (raise_exception) { PyErr_SetString(PyExc_TypeError, "Cannot convert non-sequence to std::tuple"); }
+        return false;
+      }
+      pyref seq = PySequence_Fast(ob, "expected a sequence");
+      // Sizes must match! Could we relax this condition to '<'?
+      if (PySequence_Fast_GET_SIZE((PyObject *)seq) != std::tuple_size<tuple_t>::value) {
+        if (raise_exception) { PyErr_SetString(PyExc_TypeError, "Cannot convert to std::tuple due to improper length"); }
+        return false;
       }
-    _false:
-      if (raise_exception) { PyErr_SetString(PyExc_TypeError, "Cannot convert to std::tuple"); }
-      return false;
+      return is_convertible_impl((PyObject *)seq, raise_exception, std::make_index_sequence<sizeof...(Types)>());
     }
 
     // -----------------------------------------
 
+    private:
+    template <auto... Is> static auto py2c_impl(PyObject *seq, std::index_sequence<Is...>) {
+      return std::make_tuple(py_converter<std::decay_t<Types>>::py2c(PySequence_Fast_GET_ITEM(seq, Is))...);
+    }
+
+    public:
     static tuple_t py2c(PyObject *ob) {
       pyref seq = PySequence_Fast(ob, "expected a sequence");
       return py2c_impl((PyObject *)seq, std::make_index_sequence<sizeof...(Types)>());

c++/cpp2py/converters/vector.hpp

@@ -99,11 +99,7 @@ namespace cpp2py {
       pyref seq = PySequence_Fast(ob, "expected a sequence");
       int len   = PySequence_Size(ob);
       for (int i = 0; i < len; i++) {
-        if (!py_converter<T>::is_convertible(PySequence_Fast_GET_ITEM((PyObject *)seq, i), false)) { // borrowed ref
-          if (raise_exception) {
-            auto err = std::string{"Cannot convert sequence to std::vector due to element at position "} + std::to_string(i);
-            PyErr_SetString(PyExc_TypeError, err.c_str());
-          }
+        if (!py_converter<T>::is_convertible(PySequence_Fast_GET_ITEM((PyObject *)seq, i), raise_exception)) { // borrowed ref
           return false;
         }
       }