[records] Compact constructor type parameters

Gavin Bierman gavin.bierman at oracle.com
Fri Nov 15 15:40:39 UTC 2019

Sounds good. 


> On 9 Nov 2019, at 11:47, Brian Goetz <brian.goetz at oracle.com> wrote:
> This is reasonable and probably easy to spec: when we define the canonical ctor, in addition to defining its is defined to have no type parameters.  Since the compact ctor is shorthand for a full canonical ctor, no additional spec is needed for that.  
> Sent from my iPad
>> On Nov 9, 2019, at 12:07 PM, Tagir Valeev <amaembo at gmail.com> wrote:
>> Hello!
>> Reading the latest JLS spec draft for records, chapter 8.10.5 [1] I
>> see the following:
>> A compact constructor declaration provides an alternative, succinct
>> means to declare a canonical constructor for a record type.
>> CompactConstructorDeclaration:{ Annotation } { ConstructorModifier } [
>> TypeParameters ] SimpleTypeName ConstructorBody
>> Is it really useful to allow type parameters specification for a
>> compact constructor, given that we cannot alter the formal parameters
>> list, thus we cannot use them there? Yes, we could use them to declare
>> local variables but this is an implementation detail, thus it should
>> not leak to the clients (especially given the fact that canonical
>> constructors are always public). Should not we exclude type parameters
>> from the compact constructor declaration?
>> I think we can go even further and disable type parameters for
>> explicit canonical constructor declaration (not in compact form) as
>> well. WDYT?
>> With best regards,
>> Tagir Valeev.
>> [1] http://cr.openjdk.java.net/~gbierman/jep359/jep359-20191031/specs/records-jls.html#jls-8.10.5

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