New candidate JEP: 492: Flexible Constructor Bodies (Third Preview)

[Maurizio Cimadamore]

Hi Gavin,
the changes look good, thanks! Some minor comments below:

* "If a constructor body does not begin with contain an explicit 
constructor invocation and the constructor being declared is not part of 
the primordial class Object, then the constructor body implicitly begins 
with a superclass constructor invocation "super();", an invocation of 
the constructor of its the direct superclass that takes no arguments."

Should we use the newly introduced terminology here (to make things 
extra clear)? E.g. say that if the constructor does not contain an 
explicit constructor invocation, then all statements are implicitly 
treated as epilogue, there's no prologue, and the explicit constructor 
is "super()".

* "It is a compile-time error for a constructor to directly or 
indirectly invoke itself through a series of one or more alternate 
constructor invocations."

I found this confusing -- after all constructor of A can do "new B()" 
which can then do "new A()". Does the constructor invoke itself? I think 
you mean "invoke itself _on the same receiver object_" ?

* The fixes to 8.8.7.1 and 15.9.2 look good! (the PR for them is in [1])

Maurizio



On 01/11/2024 16:04, Gavin Bierman wrote:
> Dear experts:
>
> The first draft of a spec covering JEP 492: Flexible Constructor 
> Bodies (Third Preview) is available:
>
> https://cr.openjdk.org/~gbierman/jep492/latest/
>
> (As the feature is unchanged from the second preview, this spec is the 
> same as the previous edition but with a small number of minor bugfixes.)
>
> Feel free to contact me directly or on this list with any comments.
>
> Thanks
> Gavin
>
>
>> On 2 Oct 2024, at 14:14, Mark Reinhold <mark.reinhold at oracle.com> wrote:
>>
>> https://openjdk.org/jeps/492
>>
>>  Summary: In constructors in the Java programming language, allow
>>  statements to appear before an explicit constructor invocation, i.e.,
>>  super(..) or this(..).  The statements cannot reference the instance
>>  under construction, but they can initialize its fields.  Initializing
>>  fields before invoking another constructor makes a class more reliable
>>  when methods are overridden.  This is a preview language feature.
>>
>> - Mark
>
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