Hi Archie,
Your updates to the JEP are excellent in every way. Thank you.
Alex
On 5/18/2023 3:56 PM, Archie Cobbs wrote:
Hi Alex,
Great comments, thanks....
On Thu, May 18, 2023 at 2:25 PM Alex Buckley <[email protected]
<mailto:[email protected]>> wrote:
... the Non-Goals should focus on what the end user (a developer) will
see or not see. Finally, almost no-one will be able to figure out what
this means -- "There are many ways in which the interplay between
superclass constructors and subclass initialization might be improved"
-- so please either explain (in a very small space) or remove.
Agreed - removed.
I'm saying that millions of lines of code exist because people
explicitly
coded around the restriction you're now removing, so there's a huge
amount of refactoring that is (a) possible and (b) desirable, so we
_assume_ that static analyzers and IDEs will promote this
refactoring to
their users. If you don't say this in the JEP, no-one will know it.
No-one knows as much as you about this feature, so please share :-)
Good point.. I've added some more verbiage to Risks & Assumptions.
I also added some language to highlight the fact that this
"pre-construction" context we are creating is not really new - the rules
are the same as already apply to the this()/super() parameter expressions.
So hopefully that is a big hint to any tool providers that they already
know how to treat the code in the constructor prologue.
I would like to enrich the "Implementing fail-fast" subsection by
acknowledging the fine idiom of _telescoping constructors_, where
simpler constructors delegate to richer constructors by using
`this(..)`
to pass default arguments (see https://stackoverflow.com/a/285187
<https://urldefense.com/v3/__https://stackoverflow.com/a/285187__;!!ACWV5N9M2RV99hQ!O-9cBnMpSBttTFUwyTA_mphXNEnUrb691HNu5nTJkieZQZMkA1UgNTyTpWa05uE-RnIz8ZnI_-8soiSv_GkKYHs1Sw$>).
In
any intermediate constructor of non-zero arity, being able to check the
arguments before delegation could be useful.
"Telescoping constructors" is definitely a worthy use case for this
feature... I like that and have added it.
And a good real-world example comes from none other than java.lang.Thread.
-Archie
--
Archie L. Cobbs
