move ctype pointer to stub

python-package/xgboost/_typing.py

@@ -1,6 +1,6 @@
 import ctypes
 import os
-from typing import Optional, List, Any, TypeVar, Union, Dict
+from typing import Optional, List, Any, Union, TypeVar
 
 import numpy as np
 
@@ -16,31 +16,8 @@
 cupy_t = ArrayLike  # maybe need a stub for cupy arrays
 numpy_or_cupy_t = Union[np.ndarray, cupy_t]
 
-# ctypes
 # c_bst_ulong corresponds to bst_ulong defined in xgboost/c_api.h
 c_bst_ulong = ctypes.c_uint64
 
-ctype_t = Union[
-    ctypes.c_void_p, ctypes.c_char_p, ctypes.c_int,
-    ctypes.c_float, ctypes.c_uint, ctypes.c_size_t
-]
-
-# supported numeric types
-c_numeric_t = Union[
-    ctypes.c_float, ctypes.c_double, ctypes.c_uint,
-    ctypes.c_uint64, ctypes.c_int32, ctypes.c_int64
-]
-
-# c pointer types
-c_str_ptr_t = ctypes.pointer[ctypes.c_char]
-c_str_pptr_t = ctypes.pointer[ctypes.c_char_p]
-c_float_ptr_t = ctypes.pointer[ctypes.c_float]
-
-c_numeric_ptr_t = Union[
-    ctypes.pointer[ctypes.c_float], ctypes.pointer[ctypes.c_double],
-    ctypes.pointer[ctypes.c_uint], ctypes.pointer[ctypes.c_uint64],
-    ctypes.pointer[ctypes.c_int32], ctypes.pointer[ctypes.c_int64]
-]
-
 # template parameter
 T = TypeVar("T")

python-package/xgboost/_typing.pyi

@@ -0,0 +1,45 @@
+import ctypes
+import os
+from typing import Optional, List, Any, TypeVar, Union, Dict
+
+import numpy as np
+
+# os.PathLike/string/numpy.array/scipy.sparse/pd.DataFrame/dt.Frame/cudf.DataFrame/cupy.array/dlpack
+DataType = Any
+
+# xgboost accepts some other possible types in practice due to historical reason, which is
+# lesser tested.  For now we encourage users to pass a simple list of string.
+FeatNamesT = Optional[List[str]]
+
+ArrayLike = Any
+PathLike = Union[str, os.PathLike]
+cupy_t = ArrayLike  # maybe need a stub for cupy arrays
+numpy_or_cupy_t = Union[np.ndarray, cupy_t]
+
+# ctypes
+c_bst_ulong = ctypes.c_uint64
+
+ctype_t = Union[
+    ctypes.c_void_p, ctypes.c_char_p, ctypes.c_int,
+    ctypes.c_float, ctypes.c_uint, ctypes.c_size_t
+]
+
+# supported numeric types
+c_numeric_t = Union[
+    ctypes.c_float, ctypes.c_double, ctypes.c_uint,
+    ctypes.c_uint64, ctypes.c_int32, ctypes.c_int64
+]
+
+# c pointer types
+c_str_ptr_t = ctypes.pointer[ctypes.c_char]
+c_str_pptr_t = ctypes.pointer[ctypes.c_char_p]
+c_float_ptr_t = ctypes.pointer[ctypes.c_float]
+
+c_numeric_ptr_t = Union[
+    ctypes.pointer[ctypes.c_float], ctypes.pointer[ctypes.c_double],
+    ctypes.pointer[ctypes.c_uint], ctypes.pointer[ctypes.c_uint64],
+    ctypes.pointer[ctypes.c_int32], ctypes.pointer[ctypes.c_int64]
+]
+
+# template parameter
+T = TypeVar("T")