Replace raise_ with raise from

Change-Id: I7aaeb5bc130271624335b79cf586581d6c6c34c7
References: #4600

4 files changed, 36 insertions, 64 deletions

diff --git a/lib/sqlalchemy/engine/_py_processors.py b/lib/sqlalchemy/engine/_py_processors.py
index db722a978..ea48bb493 100644
--- a/lib/sqlalchemy/engine/_py_processors.py
+++ b/lib/sqlalchemy/engine/_py_processors.py
@@ -16,8 +16,6 @@ They all share one common characteristic: None is passed through unchanged.
 import datetime
 import re
 
-from .. import util
-
 
 def str_to_datetime_processor_factory(regexp, type_):
     rmatch = regexp.match
@@ -32,13 +30,10 @@ def str_to_datetime_processor_factory(regexp, type_):
             try:
                 m = rmatch(value)
             except TypeError as err:
-                util.raise_(
-                    ValueError(
-                        "Couldn't parse %s string '%r' "
-                        "- value is not a string." % (type_.__name__, value)
-                    ),
-                    from_=err,
-                )
+                raise ValueError(
+                    "Couldn't parse %s string '%r' "
+                    "- value is not a string." % (type_.__name__, value)
+                ) from err
             if m is None:
                 raise ValueError(
                     "Couldn't parse %s string: "
diff --git a/lib/sqlalchemy/engine/base.py b/lib/sqlalchemy/engine/base.py
index b11ffd871..4f8535447 100644
--- a/lib/sqlalchemy/engine/base.py
+++ b/lib/sqlalchemy/engine/base.py
@@ -1115,9 +1115,7 @@ class Connection(ConnectionEventsTarget):
         try:
             meth = statement._execute_on_connection
         except AttributeError as err:
-            util.raise_(
-                exc.ObjectNotExecutableError(statement), replace_context=err
-            )
+            raise exc.ObjectNotExecutableError(statement) from err
         else:
             return meth(
                 self,
@@ -1670,21 +1668,15 @@ class Connection(ConnectionEventsTarget):
         invalidate_pool_on_disconnect = not is_exit_exception
 
         if self._reentrant_error:
-            util.raise_(
-                exc.DBAPIError.instance(
-                    statement,
-                    parameters,
-                    e,
-                    self.dialect.dbapi.Error,
-                    hide_parameters=self.engine.hide_parameters,
-                    dialect=self.dialect,
-                    ismulti=context.executemany
-                    if context is not None
-                    else None,
-                ),
-                with_traceback=exc_info[2],
-                from_=e,
-            )
+            raise exc.DBAPIError.instance(
+                statement,
+                parameters,
+                e,
+                self.dialect.dbapi.Error,
+                hide_parameters=self.engine.hide_parameters,
+                dialect=self.dialect,
+                ismulti=context.executemany if context is not None else None,
+            ).with_traceback(exc_info[2]) from e
         self._reentrant_error = True
         try:
             # non-DBAPI error - if we already got a context,
@@ -1773,14 +1765,11 @@ class Connection(ConnectionEventsTarget):
                         self._rollback_impl()
 
             if newraise:
-                util.raise_(newraise, with_traceback=exc_info[2], from_=e)
+                raise newraise.with_traceback(exc_info[2]) from e
             elif should_wrap:
-                util.raise_(
-                    sqlalchemy_exception, with_traceback=exc_info[2], from_=e
-                )
+                raise sqlalchemy_exception.with_traceback(exc_info[2]) from e
             else:
-                util.raise_(exc_info[1], with_traceback=exc_info[2])
-
+                raise exc_info[1].with_traceback(exc_info[2])
         finally:
             del self._reentrant_error
             if self._is_disconnect:
@@ -1844,13 +1833,11 @@ class Connection(ConnectionEventsTarget):
                 ) = ctx.is_disconnect
 
         if newraise:
-            util.raise_(newraise, with_traceback=exc_info[2], from_=e)
+            raise newraise.with_traceback(exc_info[2]) from e
         elif should_wrap:
-            util.raise_(
-                sqlalchemy_exception, with_traceback=exc_info[2], from_=e
-            )
+            raise sqlalchemy_exception.with_traceback(exc_info[2]) from e
         else:
-            util.raise_(exc_info[1], with_traceback=exc_info[2])
+            raise exc_info[1].with_traceback(exc_info[2])
 
     def _run_ddl_visitor(self, visitorcallable, element, **kwargs):
         """run a DDL visitor.
diff --git a/lib/sqlalchemy/engine/cursor.py b/lib/sqlalchemy/engine/cursor.py
index 8247987fa..bd2c092a7 100644
--- a/lib/sqlalchemy/engine/cursor.py
+++ b/lib/sqlalchemy/engine/cursor.py
@@ -587,21 +587,15 @@ class CursorResultMetaData(ResultMetaData):
 
         if raiseerr:
             if self._unpickled and isinstance(key, elements.ColumnElement):
-                util.raise_(
-                    exc.NoSuchColumnError(
-                        "Row was unpickled; lookup by ColumnElement "
-                        "is unsupported"
-                    ),
-                    replace_context=err,
-                )
+                raise exc.NoSuchColumnError(
+                    "Row was unpickled; lookup by ColumnElement "
+                    "is unsupported"
+                ) from err
             else:
-                util.raise_(
-                    exc.NoSuchColumnError(
-                        "Could not locate column in row for column '%s'"
-                        % util.string_or_unprintable(key)
-                    ),
-                    replace_context=err,
-                )
+                raise exc.NoSuchColumnError(
+                    "Could not locate column in row for column '%s'"
+                    % util.string_or_unprintable(key)
+                ) from err
         else:
             return None
 
@@ -763,10 +757,9 @@ class NoCursorDQLFetchStrategy(NoCursorFetchStrategy):
 
     def _non_result(self, result, default, err=None):
         if result.closed:
-            util.raise_(
-                exc.ResourceClosedError("This result object is closed."),
-                replace_context=err,
-            )
+            raise exc.ResourceClosedError(
+                "This result object is closed."
+            ) from err
         else:
             return default
 
@@ -1058,13 +1051,10 @@ class _NoResultMetaData(ResultMetaData):
     returns_rows = False
 
     def _we_dont_return_rows(self, err=None):
-        util.raise_(
-            exc.ResourceClosedError(
-                "This result object does not return rows. "
-                "It has been closed automatically."
-            ),
-            replace_context=err,
-        )
+        raise exc.ResourceClosedError(
+            "This result object does not return rows. "
+            "It has been closed automatically."
+        ) from err
 
     def _index_for_key(self, keys, raiseerr):
         self._we_dont_return_rows()
diff --git a/lib/sqlalchemy/engine/result.py b/lib/sqlalchemy/engine/result.py
index ff292c7d7..7d496838a 100644
--- a/lib/sqlalchemy/engine/result.py
+++ b/lib/sqlalchemy/engine/result.py
@@ -47,7 +47,7 @@ class ResultMetaData:
 
     def _key_fallback(self, key, err, raiseerr=True):
         assert raiseerr
-        util.raise_(KeyError(key), replace_context=err)
+        raise KeyError(key) from err
 
     def _raise_for_nonint(self, key):
         raise TypeError(