On Mon, 6 Feb 2023 14:32:12 GMT, Adam Sotona <[email protected]> wrote:
>> src/java.base/share/classes/jdk/internal/classfile/ClassSignature.java line
>> 34:
>>
>>> 32: * Models the generic signature of a class file, as defined by JVMS
>>> 4.7.9.
>>> 33: */
>>> 34: public sealed interface ClassSignature
>>
>> It is a bit odd to have Signature and XYZSignature in the API with the
>> latter not extending the former. I think I get what the API is aiming for
>> though - e.g. Signature is for modelling low-level "portions" of the
>> signature attributes, whereas ClassSignature, MethodSignature and friends
>> are there to model the signature attribute attached to a class, method, etc.
>
> The confusion come from simplified name. Signature probably should be called
> JavaTypeSignature according to the spec. ClassSignature and MethodSignature
> could not extend it, as it would not respect the reality. Each of them are
> completely different species. Signature (or JavaTypeSignature) on the other
> side has many sub-types.
I think you mean `TypeSignature` from JLS 4.3.4 ? If so, I get it. To me it
looks as if "Signature" really means "TypeSignature" - then it would make sense
as to why `MethodSignature::arguments` returns a `List<Signature>` (e.g.
because it should be `List<TypeSignature>`, as in the spec).
Also, from a modelling perspective, I see other problems too - in the JVMS,
type signatures are defined as follows:
TypeSignature:
FieldTypeSignature
BaseType
```
And:
FieldTypeSignature:
ClassTypeSignature
ArrayTypeSignature
TypeVariableSignature
So I'd roughly expect a type with 4 subclasses (type, then class <: type, array
<: type, tvar <: type).
But the Signature class currently has other subclasses too - such as
`ThrowableSig` - which is really only an (optional) part of method signatures.
And, similarly, it also has `TypeParam`, which is a part of method/class
signature - but is _not_ a type signature per se.
Summing up, it seems to me that the naming issue (which is not that important)
hides a bigger modelling issue.
-------------
PR: https://git.openjdk.org/jdk/pull/10982
