Sync some changes from KvikIO's Array (#290)

Pulls in a few changes from KvikIO's `Array`. Namely...

* `asarray` for easy conversion to `Array` (no-op if already an `Array`)
* Include types for a few more properties

Authors:
  - https://github.com/jakirkham

Approvers:
  - Peter Andreas Entschev (https://github.com/pentschev)
  - Lawrence Mitchell (https://github.com/wence-)

URL: #290

python/ucxx/ucxx/_lib/arr.pxd

@@ -1,6 +1,8 @@
-# SPDX-FileCopyrightText: Copyright (c) 2022-2023, NVIDIA CORPORATION & AFFILIATES.
+# SPDX-FileCopyrightText: Copyright (c) 2020-2024, NVIDIA CORPORATION & AFFILIATES.
 # SPDX-License-Identifier: BSD-3-Clause
 
+# cython: language_level=3
+
 
 from libc.stdint cimport uintptr_t
 
@@ -22,3 +24,6 @@ cdef class Array:
     cpdef bint _f_contiguous(self)
     cpdef bint _contiguous(self)
     cpdef Py_ssize_t _nbytes(self)
+
+
+cpdef Array asarray(obj)

python/ucxx/ucxx/_lib/arr.pyi

@@ -1,10 +1,12 @@
-# SPDX-FileCopyrightText: Copyright (c) 2022-2023, NVIDIA CORPORATION & AFFILIATES.
+# SPDX-FileCopyrightText: Copyright (c) 2020-2024, NVIDIA CORPORATION & AFFILIATES.
 # SPDX-License-Identifier: BSD-3-Clause
 
-from typing import Tuple
+from typing import Generic, Tuple, TypeVar
 
-class Array:
-    def __init__(self, obj: object): ...
+T = TypeVar("T")
+
+class Array(Generic[T]):
+    def __init__(self, obj: T): ...
     @property
     def c_contiguous(self) -> bool: ...
     @property
@@ -17,3 +19,9 @@ class Array:
     def shape(self) -> Tuple[int]: ...
     @property
     def strides(self) -> Tuple[int]: ...
+    @property
+    def cuda(self) -> bool: ...
+    @property
+    def obj(self) -> T: ...
+
+def asarray(obj) -> Array: ...

python/ucxx/ucxx/_lib/arr.pyx

@@ -1,6 +1,8 @@
-# SPDX-FileCopyrightText: Copyright (c) 2022-2023, NVIDIA CORPORATION & AFFILIATES.
+# SPDX-FileCopyrightText: Copyright (c) 2020-2024, NVIDIA CORPORATION & AFFILIATES.
 # SPDX-License-Identifier: BSD-3-Clause
 
+# cython: language_level=3
+
 
 from cpython.array cimport array, newarrayobject
 from cpython.buffer cimport PyBuffer_IsContiguous
@@ -295,3 +297,22 @@ cdef inline Py_ssize_t _nbytes(Py_ssize_t itemsize,
     for i in range(ndim):
         nbytes *= shape_mv[i]
     return nbytes
+
+
+cpdef Array asarray(obj):
+    """Coerce other objects to ``Array``. No-op for existing ``Array``s.
+
+    Parameters
+    ----------
+    obj: object
+        Object exposing the Python buffer protocol or ``__cuda_array_interface__``.
+
+    Returns
+    -------
+    array: Array
+        An instance of the ``Array`` class.
+    """
+    if isinstance(obj, Array):
+        return <Array>obj
+    else:
+        return Array(obj)