Re: [Libguestfs] [PATCH 4/9] qapi: Tools for sets of special feature flags in generated code

On Mon, Oct 25, 2021 at 1:25 AM Markus Armbruster <armbru(a)redhat.com&gt; wrote: > New enum QapiSpecialFeature enumerates the special feature flags. > > New helper gen_special_features() returns code to represent a > collection of special feature flags as a bitset. > > The next few commits will put them to use. > > Signed-off-by: Markus Armbruster <armbru(a)redhat.com&gt; > --- > include/qapi/util.h | 4 ++++ > scripts/qapi/gen.py | 13 +++++++++++++ > scripts/qapi/schema.py | 3 +++ > 3 files changed, 20 insertions(+) > > diff --git a/include/qapi/util.h b/include/qapi/util.h > index 257c600f99..7a8d5c7d72 100644 > --- a/include/qapi/util.h > +++ b/include/qapi/util.h > @@ -11,6 +11,10 @@ > #ifndef QAPI_UTIL_H > #define QAPI_UTIL_H > > +typedef enum { > + QAPI_DEPRECATED, > +} QapiSpecialFeature; > + > /* QEnumLookup flags */ > #define QAPI_ENUM_DEPRECATED 1 > > diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py > index 2ec1e7b3b6..9d07b88cf6 100644 > --- a/scripts/qapi/gen.py > +++ b/scripts/qapi/gen.py > @@ -29,6 +29,7 @@ > mcgen, > ) > from .schema import ( > + QAPISchemaFeature, > QAPISchemaIfCond, > QAPISchemaModule, > QAPISchemaObjectType, > @@ -37,6 +38,18 @@ > from .source import QAPISourceInfo > > > +def gen_special_features(features: QAPISchemaFeature): > + ret = '' > + sep = '' > + > + for feat in features: > + if feat.is_special(): > + ret += ('%s1u << QAPI_%s' % (sep, feat.name.upper())) > Building the constant name here "feels" fragile, but I'll trust that the test suite and/or the compiler will catch us if we accidentally goof up this mapping. In the interest of simplicity, then, "sure, why not."

> + sep = ' | ' > + > + return ret or '0' > + > Subjectively more pythonic: special_features = [f"1u << QAPI_{feat.name.upper()}" for feat in features if feat.is_special()] ret = ' | '.join(special_features) return ret or '0' A bit more dense, but more functional. Up to you, but I find join() easier to read and reason about for the presence of separators.

> + > class QAPIGen: > def __init__(self, fname: str): > self.fname = fname > diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py > index 6d5f46509a..55f82d7389 100644 > --- a/scripts/qapi/schema.py > +++ b/scripts/qapi/schema.py > @@ -725,6 +725,9 @@ def connect_doc(self, doc): > class QAPISchemaFeature(QAPISchemaMember): > role = 'feature' > > + def is_special(self): > + return self.name in ('deprecated') > + > alrighty. (Briefly wondered: is it worth naming special features as a property of the class, but with only two names, it's probably fine enough to leave it embedded in the method logic. Only a style thing and doesn't have any actual impact that I can imagine, so ... nevermind.)

> class QAPISchemaObjectTypeMember(QAPISchemaMember): > def __init__(self, name, info, typ, optional, ifcond=None, > features=None): > -- > 2.31.1 > > Well, either way: Reviewed-by: John Snow <jsnow(a)redhat.com&gt;