fix shape initialization

Author: wolfv

include/xtensor-python/pyarray.hpp

@@ -387,6 +387,7 @@ namespace xt
         const container_type& data_impl() const noexcept;
 
         friend class xcontainer<pyarray<T>>;
+        friend class pycontainer<pyarray<T>>;
     };
 
     /**************************************

include/xtensor-python/pycontainer.hpp

@@ -120,6 +120,9 @@ namespace xt
         static bool check_(pybind11::handle h);
         static PyObject* raw_array_t(PyObject* ptr);
 
+        derived_type& derived_cast();
+        const derived_type& derived_cast() const;
+
         PyArrayObject* python_array() const;
         size_type get_min_stride() const;
     };
@@ -260,6 +263,19 @@ namespace xt
         return std::max(size_type(1), std::accumulate(this->strides().cbegin(), this->strides().cend(), std::numeric_limits<size_type>::max(), min));
     }
 
+    template <class D>
+    inline auto pycontainer<D>::derived_cast() -> derived_type&
+    {
+        return *static_cast<derived_type*>(this);
+    }
+
+    template <class D>
+    inline auto pycontainer<D>::derived_cast() const -> const derived_type&
+    {
+        return *static_cast<const derived_type*>(this);
+    }
+
+
     /**
      * resizes the container.
      * @param shape the new shape
@@ -330,7 +346,11 @@ namespace xt
         }
 
         PyArray_Dims dims({reinterpret_cast<npy_intp*>(shape.data()), static_cast<int>(shape.size())});
-        PyArray_Newshape((PyArrayObject*) this->ptr(), &dims, npy_layout);
+        auto new_ptr = PyArray_Newshape((PyArrayObject*) this->ptr(), &dims, npy_layout);
+        auto old_ptr = this->ptr();
+        this->ptr() = new_ptr;
+        Py_XDECREF(old_ptr);
+        this->derived_cast().init_from_python();
     }
 
     /**

include/xtensor-python/pytensor.hpp

@@ -207,6 +207,7 @@ namespace xt
         const container_type& data_impl() const noexcept;
 
         friend class xcontainer<pytensor<T, N>>;
+        friend class pycontainer<pytensor<T, N>>;
     };
 
     /***************************

test/test_pyarray.cpp

@@ -220,8 +220,12 @@ namespace xt
         pyarray<int> a = {{1,2,3}, {4,5,6}};
         auto ptr = a.raw_data();
         a.reshape({1, 6});
+        std::vector<std::size_t> sc1({1, 6});
+        EXPECT_TRUE(std::equal(sc1.begin(), sc1.end(), a.shape().begin()) && a.shape().size() == 2);
         EXPECT_EQ(ptr, a.raw_data());
         a.reshape({6});
+        std::vector<std::size_t> sc2 = {6};
+        EXPECT_TRUE(std::equal(sc2.begin(), sc2.end(), a.shape().begin()) && a.shape().size() == 1);
         EXPECT_EQ(ptr, a.raw_data());
     }
 }