On 10/11/19 6:50 PM, Maurizio Cimadamore wrote:
On 11/10/2019 22:19, fo...@univ-mlv.fr wrote:
----- Mail original -----
De: "Brian Goetz" <brian.go...@oracle.com>
À: "Remi Forax" <fo...@univ-mlv.fr>, "amber-spec-experts"
<amber-spec-experts@openjdk.java.net>
Envoyé: Vendredi 11 Octobre 2019 22:57:23
Objet: Re: Record attribute binary format
No need. Varargs-ness is reified with the (mandated) canonical ctor.
hum, this looks like a hack, it means you can not just read the
Record attribute, you have to crawle all the methods to find the
primary constructor.
It _looks_ like an hack, but I think that, after some more thinking
it's actually more correct than what you are proposing. A record
contains a bunch of components, the components have a name and a type.
Vararg-ness is immaterial here; both
record Foo(Object[] arr) { ... }
and
record Bar(Object... arr) { ... }
Denote the same underlying state (e.g. an Object array). The only
difference between Foo and Bar is that their _construction protocol_
is different (which might also mean, in the future, that Bar will get
more liberal _deconstruction_ protocols too!); but this is cleanly
captured in the canonical constructor method_info.
Pedagolical test: would an 'isVarargs()' predicate on the core
reflection record component be acceptable?
that method as already added to j.l.r.RecordComponent, see [1],
Ugh, I don't think so. Varargs is a method concept; record components
are a bit ephemeral, yes, but they are definitively _not_ methods.
Maurizio
Vicente
[1]
http://hg.openjdk.java.net/amber/amber/file/df5e1c317777/src/java.base/share/classes/java/lang/reflect/RecordComponent.java#l209
and if we take a look to the past, we have added access flags to
methods, fields and classes, so there is a non negligible chance that
we will want to do the same to record components in the future.
Rémi
On 10/11/2019 4:43 PM, Remi Forax wrote:
It seems we have to add an access_flag for each record component
because we have
to mark if the record component is a varargs or not.
So the format should be
Record_attribute {
u2 attribute_name_index;
u4 attribute_length;
u2 number_of_record_components;
{ u2 component_access_flags;
u2 component_name_index;
u2 component_descriptor_index;
u2 attribute_count;
attribute_info attributes[attributes_count];
}
}
with the component_access_flags allowing ACC_VARARGS.
Rémi
