RFR 9: 8138963 : java.lang.Objects new method to default to non-null

[John Rose]

My point, and Daniel's point, is that requireNonNull can be re-interpreted (ret-conned) as enforcing a post-condition instead of a pre-condition.  (The logic of JDK 8 rNN allows either view equally.)  Then all of these API points hang together very nicely.

After I tinkered with the cross-simulation to Optional this insight just fell out of the equations:  It's a rare case of Math improving English.

Roger, it's a judgement call, but I don't think the API points differ as much as you say they do.

— John

On Oct 9, 2015, at 4:41 AM, Brian Goetz <brian.goetz at oracle.com> wrote:
> 
> The semantics of require* here was that it should throw if the precondition is violated.  That lead to a different naming direction than the current use case, in which null is an expected value rather than an error.  
> 
> Sent from my iPhone
> 
>> On Oct 9, 2015, at 11:58 AM, Stephen Colebourne <scolebourne at joda.org> wrote:
>> 
>>> On 9 October 2015 at 01:31, John Rose <john.r.rose at oracle.com> wrote:
>>> This leads me to yet another bikeshed color, FWIW:
>>> 
>>> - T requireNonNull(T) (cf. Optional::get)
>>> - T requireNonNullElse(T,T) (cf. Optional::orElse)
>>> - T requireNonNullElseGet(T,Supplier<T>) (cf. Optional::orElseGet)
>>> - T requireNonNullElseThrow(T,Supplier<X>) (cf. Optional::orElseThrow)
>>> - T requireNonNull(T,String) (shorthand for common use of requireNonNullElseThrow)
>> 
>> Note that there is already a new method in JDK 8 not listed above:
>> requireNonNull(T, Supplier<String>)
>> As such, I'm not convinced that requireNonNullElseThrow will pull its weight.
>> 
>> I can see the benefits of this consistency of naming. (FWIW, I think
>> the "require" prefix was a mistake, but that ship has sailed). If this
>> naming is chosen, I'd like to see all the methods next to one another
>> in the source file, which involves moving the method added in JDK 8.
>> 
>> Stephen