Setup scopefunc when initialising Flask-SQLAlchemy. Does not need t…

…o add another argument to `create_scoped_session`.

flaskext/sqlalchemy.py

@@ -586,13 +586,22 @@ class User(db.Model):
 
     .. versionadded:: 0.10
        The `session_options` parameter was added.
+
+    .. versionadded:: 0.16
+       `scopefunc` is now accepted on `session_options`. It allows specifying
+        a custom function which will define the SQLAlchemy session's scoping.
     """
 
     def __init__(self, app=None, use_native_unicode=True,
                  session_extensions=None, session_options=None):
         self.use_native_unicode = use_native_unicode
         self.session_extensions = to_list(session_extensions, []) + \
                                   [_SignallingSessionExtension()]
+
+        session_options.set_default(
+            'scopefunc', _request_ctx_stack.__ident_func__
+        )
+
         self.session = self.create_scoped_session(session_options)
         self.Model = self.make_declarative_base()
         self._engine_lock = Lock()
@@ -611,17 +620,11 @@ def metadata(self):
         """Returns the metadata"""
         return self.Model.metadata
 
-    def create_scoped_session(self, options=None, scopefunc=None):
-        """Helper factory method that creates a scoped session.
-
-        .. versionadded:: 0.16
-            The `scopefunc` parameter was added.
-
-        """
+    def create_scoped_session(self, options=None):
+        """Helper factory method that creates a scoped session."""
         if options is None:
             options = {}
-        if scopefunc is None:
-            scopefunc = _request_ctx_stack.__ident_func__
+        scopefunc=options.pop('scopefunc', None)
         return orm.scoped_session(
             partial(_SignallingSession, self, **options), scopefunc=scopefunc
         )