ENH: Implement the DLPack Array API protocols for ndarray.

doc/neps/nep-0047-array-api-standard.rst

@@ -338,9 +338,10 @@ the options already present in NumPy are:
 
 Adding support for DLPack to NumPy entails:
 
-- Adding a ``ndarray.__dlpack__`` method.
-- Adding a ``from_dlpack`` function, which takes as input an object
-  supporting ``__dlpack__``, and returns an ``ndarray``.
+- Adding a ``ndarray.__dlpack__()`` method which returns a ``dlpack`` C
+  structure wrapped in a ``PyCapsule``.
+- Adding a ``np._from_dlpack(obj)`` function, where ``obj`` supports
+  ``__dlpack__()``, and returns an ``ndarray``.
 
 DLPack is currently a ~200 LoC header, and is meant to be included directly, so
 no external dependency is needed. Implementation should be straightforward.

doc/release/upcoming_changes/19083.new_feature.rst

@@ -0,0 +1,6 @@
+Add NEP 47-compatible dlpack support
+------------------------------------
+
+Add a ``ndarray.__dlpack__()`` method which returns a ``dlpack`` C structure
+wrapped in a ``PyCapsule``. Also add a ``np._from_dlpack(obj)`` function, where
+``obj`` supports ``__dlpack__()``, and returns an ``ndarray``.

numpy/__init__.pyi

@@ -1413,6 +1413,7 @@ _SupportsBuffer = Union[
 
 _T = TypeVar("_T")
 _T_co = TypeVar("_T_co", covariant=True)
+_T_contra = TypeVar("_T_contra", contravariant=True)
 _2Tuple = Tuple[_T, _T]
 _CastingKind = L["no", "equiv", "safe", "same_kind", "unsafe"]
 
@@ -1432,6 +1433,10 @@ _ArrayTD64_co = NDArray[Union[bool_, integer[Any], timedelta64]]
 # Introduce an alias for `dtype` to avoid naming conflicts.
 _dtype = dtype
 
+# `builtins.PyCapsule` unfortunately lacks annotations as of the moment;
+# use `Any` as a stopgap measure
+_PyCapsule = Any
+
 class _SupportsItem(Protocol[_T_co]):
     def item(self, args: Any, /) -> _T_co: ...
 
@@ -2439,6 +2444,12 @@ class ndarray(_ArrayOrScalarCommon, Generic[_ShapeType, _DType_co]):
     def __ior__(self: NDArray[signedinteger[_NBit1]], other: _ArrayLikeInt_co) -> NDArray[signedinteger[_NBit1]]: ...
     @overload
     def __ior__(self: NDArray[object_], other: Any) -> NDArray[object_]: ...
+    @overload
+    def __ior__(self: NDArray[_ScalarType], other: _RecursiveSequence) -> NDArray[_ScalarType]: ...
+    @overload
+    def __dlpack__(self: NDArray[number[Any]], *, stream: None = ...) -> _PyCapsule: ...
+    @overload
+    def __dlpack_device__(self) -> Tuple[int, L[0]]: ...
 
     # Keep `dtype` at the bottom to avoid name conflicts with `np.dtype`
     @property
@@ -4320,3 +4331,9 @@ class chararray(ndarray[_ShapeType, _CharDType]):
 
 # NOTE: Deprecated
 # class MachAr: ...
+
+class _SupportsDLPack(Protocol[_T_contra]):
+    def __dlpack__(self, *, stream: None | _T_contra = ...) -> _PyCapsule: ...
+
+def _from_dlpack(__obj: _SupportsDLPack[None]) -> NDArray[Any]: ...
+

numpy/array_api/__init__.py

@@ -136,7 +136,7 @@
     empty,
     empty_like,
     eye,
-    from_dlpack,
+    _from_dlpack,
     full,
     full_like,
     linspace,
@@ -155,7 +155,7 @@
     "empty",
     "empty_like",
     "eye",
-    "from_dlpack",
+    "_from_dlpack",
     "full",
     "full_like",
     "linspace",

numpy/array_api/_creation_functions.py

@@ -151,7 +151,7 @@ def eye(
     return Array._new(np.eye(n_rows, M=n_cols, k=k, dtype=dtype))
 
 
-def from_dlpack(x: object, /) -> Array:
+def _from_dlpack(x: object, /) -> Array:
     # Note: dlpack support is not yet implemented on Array
     raise NotImplementedError("DLPack support is not yet implemented")
 

numpy/core/_add_newdocs.py

@@ -1573,6 +1573,19 @@
         array_function_like_doc,
     ))
 
+add_newdoc('numpy.core.multiarray', '_from_dlpack',
+    """
+    _from_dlpack(x, /)
+
+    Create a NumPy array from an object implementing the ``__dlpack__``
+    protocol.
+
+    See Also
+    --------
+    `Array API documentation
+    <https://data-apis.org/array-api/latest/design_topics/data_interchange.html#syntax-for-data-interchange-with-dlpack>`_
+    """)
+
 add_newdoc('numpy.core', 'fastCopyAndTranspose',
     """_fastCopyAndTranspose(a)""")
 
@@ -2263,6 +2276,15 @@
 add_newdoc('numpy.core.multiarray', 'ndarray', ('__array_struct__',
     """Array protocol: C-struct side."""))
 
+add_newdoc('numpy.core.multiarray', 'ndarray', ('__dlpack__',
+    """a.__dlpack__(*, stream=None)
+
+    DLPack Protocol: Part of the Array API."""))
+
+add_newdoc('numpy.core.multiarray', 'ndarray', ('__dlpack_device__',
+    """a.__dlpack_device__()
+
+    DLPack Protocol: Part of the Array API."""))
 
 add_newdoc('numpy.core.multiarray', 'ndarray', ('base',
     """

numpy/core/code_generators/genapi.py

@@ -41,6 +41,7 @@
              join('multiarray', 'datetime_busdaycal.c'),
              join('multiarray', 'datetime_strings.c'),
              join('multiarray', 'descriptor.c'),
+             join('multiarray', 'dlpack.c'),
              join('multiarray', 'dtypemeta.c'),
              join('multiarray', 'einsum.c.src'),
              join('multiarray', 'flagsobject.c'),

numpy/core/multiarray.py

@@ -14,27 +14,28 @@
 # do not change them. issue gh-15518
 # _get_ndarray_c_version is semi-public, on purpose not added to __all__
 from ._multiarray_umath import (
-    _fastCopyAndTranspose, _flagdict, _insert, _reconstruct, _vec_string,
-    _ARRAY_API, _monotonicity, _get_ndarray_c_version, _set_madvise_hugepage,
+    _fastCopyAndTranspose, _flagdict, _from_dlpack, _insert, _reconstruct,
+    _vec_string, _ARRAY_API, _monotonicity, _get_ndarray_c_version,
+    _set_madvise_hugepage,
     )
 
 __all__ = [
     '_ARRAY_API', 'ALLOW_THREADS', 'BUFSIZE', 'CLIP', 'DATETIMEUNITS',
     'ITEM_HASOBJECT', 'ITEM_IS_POINTER', 'LIST_PICKLE', 'MAXDIMS',
     'MAY_SHARE_BOUNDS', 'MAY_SHARE_EXACT', 'NEEDS_INIT', 'NEEDS_PYAPI',
     'RAISE', 'USE_GETITEM', 'USE_SETITEM', 'WRAP', '_fastCopyAndTranspose',
-    '_flagdict', '_insert', '_reconstruct', '_vec_string', '_monotonicity',
-    'add_docstring', 'arange', 'array', 'asarray', 'asanyarray',
-    'ascontiguousarray', 'asfortranarray', 'bincount', 'broadcast',
-    'busday_count', 'busday_offset', 'busdaycalendar', 'can_cast',
+    '_flagdict', '_from_dlpack', '_insert', '_reconstruct', '_vec_string',
+    '_monotonicity', 'add_docstring', 'arange', 'array', 'asarray',
+    'asanyarray', 'ascontiguousarray', 'asfortranarray', 'bincount',
+    'broadcast', 'busday_count', 'busday_offset', 'busdaycalendar', 'can_cast',
     'compare_chararrays', 'concatenate', 'copyto', 'correlate', 'correlate2',
     'count_nonzero', 'c_einsum', 'datetime_as_string', 'datetime_data',
     'dot', 'dragon4_positional', 'dragon4_scientific', 'dtype',
     'empty', 'empty_like', 'error', 'flagsobj', 'flatiter', 'format_longfloat',
-    'frombuffer', 'fromfile', 'fromiter', 'fromstring', 'get_handler_name',
-    'inner', 'interp', 'interp_complex', 'is_busday', 'lexsort',
-    'matmul', 'may_share_memory', 'min_scalar_type', 'ndarray', 'nditer',
-    'nested_iters', 'normalize_axis_index', 'packbits',
+    'frombuffer', 'fromfile', 'fromiter', 'fromstring',
+    'get_handler_name', 'inner', 'interp', 'interp_complex', 'is_busday',
+    'lexsort', 'matmul', 'may_share_memory', 'min_scalar_type', 'ndarray',
+    'nditer', 'nested_iters', 'normalize_axis_index', 'packbits',
     'promote_types', 'putmask', 'ravel_multi_index', 'result_type', 'scalar',
     'set_datetimeparse_function', 'set_legacy_print_mode', 'set_numeric_ops',
     'set_string_function', 'set_typeDict', 'shares_memory',
@@ -46,6 +47,7 @@
 scalar.__module__ = 'numpy.core.multiarray'
 
 
+_from_dlpack.__module__ = 'numpy'
 arange.__module__ = 'numpy'
 array.__module__ = 'numpy'
 asarray.__module__ = 'numpy'

numpy/core/numeric.py

@@ -13,8 +13,8 @@
     WRAP, arange, array, asarray, asanyarray, ascontiguousarray,
     asfortranarray, broadcast, can_cast, compare_chararrays,
     concatenate, copyto, dot, dtype, empty,
-    empty_like, flatiter, frombuffer, fromfile, fromiter, fromstring,
-    inner, lexsort, matmul, may_share_memory,
+    empty_like, flatiter, frombuffer, _from_dlpack, fromfile, fromiter,
+    fromstring, inner, lexsort, matmul, may_share_memory,
     min_scalar_type, ndarray, nditer, nested_iters, promote_types,
     putmask, result_type, set_numeric_ops, shares_memory, vdot, where,
     zeros, normalize_axis_index)
@@ -41,7 +41,7 @@
     'newaxis', 'ndarray', 'flatiter', 'nditer', 'nested_iters', 'ufunc',
     'arange', 'array', 'asarray', 'asanyarray', 'ascontiguousarray',
     'asfortranarray', 'zeros', 'count_nonzero', 'empty', 'broadcast', 'dtype',
-    'fromstring', 'fromfile', 'frombuffer', 'where',
+    'fromstring', 'fromfile', 'frombuffer', '_from_dlpack', 'where',
     'argwhere', 'copyto', 'concatenate', 'fastCopyAndTranspose', 'lexsort',
     'set_numeric_ops', 'can_cast', 'promote_types', 'min_scalar_type',
     'result_type', 'isfortran', 'empty_like', 'zeros_like', 'ones_like',

numpy/core/setup.py

@@ -740,6 +740,7 @@ def gl_if_msvc(build_cmd):
     #######################################################################
 
     common_deps = [
+            join('src', 'common', 'dlpack', 'dlpack.h'),
             join('src', 'common', 'array_assign.h'),
             join('src', 'common', 'binop_override.h'),
             join('src', 'common', 'cblasfuncs.h'),
@@ -749,6 +750,7 @@ def gl_if_msvc(build_cmd):
             join('src', 'common', 'npy_cblas.h'),
             join('src', 'common', 'npy_config.h'),
             join('src', 'common', 'npy_ctypes.h'),
+            join('src', 'common', 'npy_dlpack.h'),
             join('src', 'common', 'npy_extint128.h'),
             join('src', 'common', 'npy_import.h'),
             join('src', 'common', 'npy_hashtable.h'),
@@ -881,6 +883,7 @@ def gl_if_msvc(build_cmd):
             join('src', 'multiarray', 'datetime_busday.c'),
             join('src', 'multiarray', 'datetime_busdaycal.c'),
             join('src', 'multiarray', 'descriptor.c'),
+            join('src', 'multiarray', 'dlpack.c'),
             join('src', 'multiarray', 'dtypemeta.c'),
             join('src', 'multiarray', 'dragon4.c'),
             join('src', 'multiarray', 'dtype_transfer.c'),