exc.py 文件源码

def instance(cls, statement, params,
                 orig, dbapi_base_err,
                 connection_invalidated=False,
                 dialect=None):
        # Don't ever wrap these, just return them directly as if
        # DBAPIError didn't exist.
        if (isinstance(orig, BaseException) and
                not isinstance(orig, Exception)) or \
                isinstance(orig, DontWrapMixin):
            return orig

        if orig is not None:
            # not a DBAPI error, statement is present.
            # raise a StatementError
            if not isinstance(orig, dbapi_base_err) and statement:
                return StatementError(
                    "(%s.%s) %s" %
                    (orig.__class__.__module__, orig.__class__.__name__,
                     orig),
                    statement, params, orig
                )

            glob = globals()
            for super_ in orig.__class__.__mro__:
                name = super_.__name__
                if dialect:
                    name = dialect.dbapi_exception_translation_map.get(
                        name, name)
                if name in glob and issubclass(glob[name], DBAPIError):
                    cls = glob[name]
                    break

        return cls(statement, params, orig, connection_invalidated)