From a952b00983c8cf113572554105648a3978e951de Mon Sep 17 00:00:00 2001
From: Zuhair Ali-Khan <54608785+zalikh2@users.noreply.github.com>
Date: Thu, 28 May 2020 12:55:14 -0500
Subject: [PATCH 1/3] ENH: Chain extensions in numpy and numpy/core

---
 numpy/core/_dtype.py      | 4 ++--
 numpy/core/fromnumeric.py | 4 ++--
 numpy/core/records.py     | 8 ++++----
 numpy/ctypeslib.py        | 8 ++++----
 4 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/numpy/core/_dtype.py b/numpy/core/_dtype.py
index 6b0ec59039a8..e4d92bda2c96 100644
--- a/numpy/core/_dtype.py
+++ b/numpy/core/_dtype.py
@@ -24,11 +24,11 @@
 def _kind_name(dtype):
     try:
         return _kind_to_stem[dtype.kind]
-    except KeyError:
+    except KeyError as e:
         raise RuntimeError(
             "internal dtype error, unknown kind {!r}"
             .format(dtype.kind)
-        )
+        ) from e
 
 
 def __str__(dtype):
diff --git a/numpy/core/fromnumeric.py b/numpy/core/fromnumeric.py
index 0c63bcf7363b..2b88ccedfe65 100644
--- a/numpy/core/fromnumeric.py
+++ b/numpy/core/fromnumeric.py
@@ -536,9 +536,9 @@ def put(a, ind, v, mode='raise'):
     """
     try:
         put = a.put
-    except AttributeError:
+    except AttributeError as e:
         raise TypeError("argument 1 must be numpy.ndarray, "
-                        "not {name}".format(name=type(a).__name__))
+                        "not {name}".format(name=type(a).__name__)) from e
 
     return put(ind, v, mode=mode)
 
diff --git a/numpy/core/records.py b/numpy/core/records.py
index 7e1c0d591020..293d56599279 100644
--- a/numpy/core/records.py
+++ b/numpy/core/records.py
@@ -461,8 +461,8 @@ def __getattribute__(self, attr):
         fielddict = ndarray.__getattribute__(self, 'dtype').fields
         try:
             res = fielddict[attr][:2]
-        except (TypeError, KeyError):
-            raise AttributeError("recarray has no attribute %s" % attr)
+        except (TypeError, KeyError) as e:
+            raise AttributeError("recarray has no attribute %s" % attr) from e
         obj = self.getfield(*res)
 
         # At this point obj will always be a recarray, since (see
@@ -509,8 +509,8 @@ def __setattr__(self, attr, val):
                     return ret
         try:
             res = fielddict[attr][:2]
-        except (TypeError, KeyError):
-            raise AttributeError("record array has no attribute %s" % attr)
+        except (TypeError, KeyError) as e:
+            raise AttributeError("record array has no attribute %s" % attr) from e
         return self.setfield(val, *res)
 
     def __getitem__(self, indx):
diff --git a/numpy/ctypeslib.py b/numpy/ctypeslib.py
index ec3cdc33d5c1..94dc0553fa37 100644
--- a/numpy/ctypeslib.py
+++ b/numpy/ctypeslib.py
@@ -297,8 +297,8 @@ def ndpointer(dtype=None, ndim=None, shape=None, flags=None):
         if num is None:
             try:
                 flags = [x.strip().upper() for x in flags]
-            except Exception:
-                raise TypeError("invalid flags specification")
+            except Exception as e:
+                raise TypeError("invalid flags specification") from e
             num = _num_fromflags(flags)
 
     # normalize shape to an Optional[tuple]
@@ -377,10 +377,10 @@ def _ctype_from_dtype_scalar(dtype):
         dtype_native = dtype.newbyteorder('=')
         try:
             ctype = _scalar_type_map[dtype_native]
-        except KeyError:
+        except KeyError as e:
             raise NotImplementedError(
                 "Converting {!r} to a ctypes type".format(dtype)
-            )
+            ) from e
 
         if dtype_with_endian.byteorder == '>':
             ctype = ctype.__ctype_be__

From eb371c1a127b09bb7e60865a4764850b40584186 Mon Sep 17 00:00:00 2001
From: Zuhair Ali-Khan <zaak7179@gmail.com>
Date: Fri, 29 May 2020 15:20:49 -0500
Subject: [PATCH 2/3] MAINT: Implement feedback to change extension chaining

---
 numpy/core/_dtype.py | 2 +-
 numpy/ctypeslib.py   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/numpy/core/_dtype.py b/numpy/core/_dtype.py
index e4d92bda2c96..76d0b814968a 100644
--- a/numpy/core/_dtype.py
+++ b/numpy/core/_dtype.py
@@ -28,7 +28,7 @@ def _kind_name(dtype):
         raise RuntimeError(
             "internal dtype error, unknown kind {!r}"
             .format(dtype.kind)
-        ) from e
+        ) from None
 
 
 def __str__(dtype):
diff --git a/numpy/ctypeslib.py b/numpy/ctypeslib.py
index 94dc0553fa37..76ba838b7a5a 100644
--- a/numpy/ctypeslib.py
+++ b/numpy/ctypeslib.py
@@ -380,7 +380,7 @@ def _ctype_from_dtype_scalar(dtype):
         except KeyError as e:
             raise NotImplementedError(
                 "Converting {!r} to a ctypes type".format(dtype)
-            ) from e
+            ) from None
 
         if dtype_with_endian.byteorder == '>':
             ctype = ctype.__ctype_be__

From a4f28efbb2fa4cdde9b36de97226ee61df81d7e0 Mon Sep 17 00:00:00 2001
From: Zuhair Ali-Khan <zaak7179@gmail.com>
Date: Fri, 29 May 2020 16:41:01 -0500
Subject: [PATCH 3/3] MAINT: Update numpy/core/records.py

Co-authored-by: Ross Barnowski <rossbar@berkeley.edu>
---
 numpy/core/records.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/numpy/core/records.py b/numpy/core/records.py
index 293d56599279..464615450605 100644
--- a/numpy/core/records.py
+++ b/numpy/core/records.py
@@ -510,7 +510,9 @@ def __setattr__(self, attr, val):
         try:
             res = fielddict[attr][:2]
         except (TypeError, KeyError) as e:
-            raise AttributeError("record array has no attribute %s" % attr) from e
+            raise AttributeError(
+                "record array has no attribute %s" % attr
+            ) from e
         return self.setfield(val, *res)
 
     def __getitem__(self, indx):