ENH: For compatibility, use an exception type that subclasses both original types

eric-wieser · eric-wieser · commit eb642f1b6533 · 2017-02-20T22:03:07.000Z
diff --git a/numpy/core/_internal.py b/numpy/core/_internal.py
@@ -630,3 +630,6 @@ def _gcd(a, b):
 # Exception used in shares_memory()
 class TooHardError(RuntimeError):
     pass
+
+class AxisError(ValueError, IndexError):
+    pass
diff --git a/numpy/core/numeric.py b/numpy/core/numeric.py
@@ -27,7 +27,7 @@
                     ERR_DEFAULT, PINF, NAN)
 from . import numerictypes
 from .numerictypes import longlong, intc, int_, float_, complex_, bool_
-from ._internal import TooHardError
+from ._internal import TooHardError, AxisError
 
 bitwise_not = invert
 ufunc = type(sin)
@@ -65,7 +65,7 @@
     'True_', 'bitwise_not', 'CLIP', 'RAISE', 'WRAP', 'MAXDIMS', 'BUFSIZE',
     'ALLOW_THREADS', 'ComplexWarning', 'full', 'full_like', 'matmul',
     'shares_memory', 'may_share_memory', 'MAY_SHARE_BOUNDS', 'MAY_SHARE_EXACT',
-    'TooHardError',
+    'TooHardError', 'AxisError'
     ]
 
 
diff --git a/numpy/core/src/multiarray/common.h b/numpy/core/src/multiarray/common.h
@@ -144,7 +144,21 @@ check_and_adjust_axis(int *axis, int ndim)
 {
     /* Check that index is valid, taking into account negative indices */
     if (NPY_UNLIKELY((*axis < -ndim) || (*axis >= ndim))) {
-        PyErr_Format(PyExc_IndexError,
+        /*
+         * Load the exception type, if we don't already have it. Unfortunately
+         * we don't have access to npy_cache_import here
+         */
+        static PyObject *AxisError_cls = NULL;
+        if (AxisError_cls == NULL) {
+            PyObject *mod = PyImport_ImportModule("numpy.core._internal");
+
+            if (mod != NULL) {
+                AxisError_cls = PyObject_GetAttrString(mod, "AxisError");
+                Py_DECREF(mod);
+            }
+        }
+
+        PyErr_Format(AxisError_cls,
                      "axis %d is out of bounds for array of dimension %d",
                      *axis, ndim);
         return -1;
