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

[John Rose]

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