[9] RFR (M): 8050052: Small cleanups in java.lang.invoke code

[Remi Forax]

On 07/18/2014 03:54 AM, John Rose wrote:
> FTR, I captured this issue:
>
>    https://bugs.openjdk.java.net/browse/JDK-8051294
>
> (Wish they were all so easy to catch.)
>
> — John

Hi John,
I like the way the proposed API is composable but i fear that people 
will still forget to first call throwIfUnchecked() most of the time.

I think we should not implement a throwSuppressedIf because a suppressed 
exception is not a primary one thus it's a more an information when 
debugging than an exception a code should act upon.

I'm not sure that looking recursively for a cause ( :) ) is a good idea, 
changing the behavior of a program because an exception buried under 10 
others doesn't seem appealing to me.
Also there is a bug hidden in your implementation of throwCauseIf, you 
return the value of cause.throwCauseIf instead of this.

cheers,
Rémi

>
> On Jul 17, 2014, at 5:12 PM, John Rose <john.r.rose at oracle.com> wrote:
>
>> On Jul 16, 2014, at 11:20 AM, Peter Levart <peter.levart at gmail.com> wrote:
>>
>>> An alternative could be:
>>>
>>> public Throwable throwIfUnchecked() {
>>>    if (this instanceof RuntimeException) throw (RuntimeException) this;
>>>    if (this instanceof Error) throw (Error) this;
>>> return this;
>>> }
>>>
>>> Then use it like:
>>>
>>>    try {
>>>        ...
>>>    } catch (Throwable t) {
>>>        throw new WrapperException(t.throwIfUnchecked());
>>>    }
>> I like this one.  (I wish we could declare This types, so that TYPEOF[t.throwIfUnchecked()] == TYPEOF[t].)
>>
>> It puts the throw of the "less dangerous" exception type inside the subroutine, making the wrapping and the "more dangerous" (more ad hoc) exception be explicit and in-line.
>>
>> To complete the picture, add:
>>
>> public <X extends Throwable> Throwable throwIf(Class<X> exClass) throws X {
>>    if (exClass.isInstance(this)) throw exClass.cast(this);
>>    return this;
>> }
>>
>> ...to be used as:
>>
>>    try {
>>        ...
>>    } catch (Throwable t) {
>>        t.throwIfUnchecked().throwIf(X.class).throwIf(Y.class).throwIf(Z.class);
>>        throw new WrapperException(t);
>>    }
>>
>> Or some other combination of sequential and/or fluent calls.
>>
>> — John