Future.resultNow()

[forax at univ-mlv.fr]

> From: "Alex Otenko" <oleksandr.otenko at gmail.com>
> To: "Remi Forax" <forax at univ-mlv.fr>
> Cc: "loom-dev" <loom-dev at openjdk.java.net>
> Sent: Samedi 20 Novembre 2021 22:49:01
> Subject: Re: Future.resultNow()

> No, I am not afraid :)

> I just think introspecting the chain of causes is brittle - in the sense that it
> relies on a specific implementation wrapping the exception in a particular way.

As Brian said, IllegalStateException is not an exception you should ever catch like NPE or AIOOBE, it's equivalent to a ReadTheFuckingManualException, 
it's an error raised because the developer has misunderstood how the API works, so providing the cause (maybe as an error message) helps to fix the bug. 

> Alex

Rémi 

> On Sat, 20 Nov 2021, 21:44 , < [ mailto:forax at univ-mlv.fr | forax at univ-mlv.fr ]
> > wrote:

>>> From: "Alex Otenko" < [ mailto:oleksandr.otenko at gmail.com |
>>> oleksandr.otenko at gmail.com ] >
>>> To: "Remi Forax" < [ mailto:forax at univ-mlv.fr | forax at univ-mlv.fr ] >
>>> Cc: "loom-dev" < [ mailto:loom-dev at openjdk.java.net | loom-dev at openjdk.java.net
>>> ] >
>>> Sent: Samedi 20 Novembre 2021 21:10:59
>>> Subject: Re: Future.resultNow()

>>> I wouldn't expect it to contain the exact cause (why the cause, and not the
>>> cause of the cause of the cause), and expect exceptionNow to be the source of
>>> truth.

>> Are you afraid that people will catch the ISE to extract the exception instead
>> of using Future.get() and catch the ExecutionException to extract the exception
>> ?
>> This is a valid concern, ExecutionException is checked and ISE is not, if you
>> provide two ways to get the same thing, i believe people will go with the
>> method that throws an unchecked exception.

>> So perhaps, instead of using the cause field, the error message of the ISE
>> should contain a string version of the exception like toString() does.

>>> Alex

>> Rémi

>>> On Sat, 20 Nov 2021, 19:14 Remi Forax, < [ mailto:forax at univ-mlv.fr |
>>> forax at univ-mlv.fr ] > wrote:

>>>> If a callable throws an exception, Future.resultNow() throws an ISE but forget
>>>> to set the resulting exception as the cause of the ISE.

>>>> regards,
>>>> Rémi