| Message ID | 20230215000011.1725012-7-jsnow@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | qapi: static typing conversion, pt5c | expand |
John Snow <jsnow@redhat.com> writes: > With the two major JSON-ish type hierarchies clarified for distinct > purposes; QAPIExpression for parsed expressions and JSONValue for > introspection data, remove this FIXME as no longer an action item. > > A third JSON-y data type, _ExprValue, is not meant to represent JSON in > the abstract but rather only the possible legal return values from a > single function, get_expr(). It isn't appropriate to attempt to merge it > with either of the above two types. > > In theory, it may be possible to define a completely agnostic > one-size-fits-all JSON type hierarchy that any other user could borrow - > in practice, it's tough to wrangle the differences between invariant, > covariant and contravariant types: input and output parameters demand > different properties of such a structure. > > However, QAPIExpression serves to authoritatively type user input to the > QAPI parser, while JSONValue serves to authoritatively type qapi > generator *output* to be served back to client users at runtime via > QMP. The AST for these two types are different and cannot be wholly > merged into a unified syntax. > > They could, in theory, share some JSON primitive definitions. In > practice, this is currently more trouble than it's worth with mypy's > current expressive power. As such, declare this "done enough for now". > > Signed-off-by: John Snow <jsnow@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com>
diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py index d570086e1a9..878f90b4583 100644 --- a/scripts/qapi/parser.py +++ b/scripts/qapi/parser.py @@ -42,10 +42,6 @@ _ExprValue = Union[List[object], Dict[str, object], str, bool] -# FIXME: Consolidate and centralize definitions for _ExprValue and -# JSONValue; currently scattered across several modules. - - class QAPIExpression(Dict[str, object]): # pylint: disable=too-few-public-methods def __init__(self,
With the two major JSON-ish type hierarchies clarified for distinct purposes; QAPIExpression for parsed expressions and JSONValue for introspection data, remove this FIXME as no longer an action item. A third JSON-y data type, _ExprValue, is not meant to represent JSON in the abstract but rather only the possible legal return values from a single function, get_expr(). It isn't appropriate to attempt to merge it with either of the above two types. In theory, it may be possible to define a completely agnostic one-size-fits-all JSON type hierarchy that any other user could borrow - in practice, it's tough to wrangle the differences between invariant, covariant and contravariant types: input and output parameters demand different properties of such a structure. However, QAPIExpression serves to authoritatively type user input to the QAPI parser, while JSONValue serves to authoritatively type qapi generator *output* to be served back to client users at runtime via QMP. The AST for these two types are different and cannot be wholly merged into a unified syntax. They could, in theory, share some JSON primitive definitions. In practice, this is currently more trouble than it's worth with mypy's current expressive power. As such, declare this "done enough for now". Signed-off-by: John Snow <jsnow@redhat.com> --- scripts/qapi/parser.py | 4 ---- 1 file changed, 4 deletions(-)