trying out the prototype

[Joe Darcy]

Gernot Neppert wrote:
> 2010/8/24 Joe Darcy <joe.darcy at oracle.com>:
>   
>> With N resources, there are possibly N+1 exceptions that can come out of the
>> try-with-resources statement, 1 from the block itself and 1 from each of the
>> close calls.  Only one of those exceptions can be the one which gets
>> propagated out of the block.
>>
>> As covered in the other recent thread, the first exception thrown is
>> estimated to be the most informative one about what actually went wrong.
>>
>> -Joe
>>
>>     
>
>
> What I do understand is that the exception thrown from the block is
> considered more important than the exception thrown by the same
> resource afterwards, when it is being closed.
>
> I just doubt that you can make a similarily educated guess about the
> relative importance of exceptions thrown by unrelated resources.
> Here is a simple example:
>
> try(Writer out = new FileWriter("output.txt"; Reader in = new
> FileReader("input.txt"))
> {
> // Code to copy from in to out.
> }
>
> Now, if the constructor of 'in' throws a (relatively harmless)
> FileNotFoundException, the much more serious DiskFullException thrown
> by the close() method of 'out' will be lost.
>   

It is trivial to generate situations where any fixed policy of 
suppressing exceptions gives the "wrong" answer about propagating the 
most informative exception.

The coin-dev list has hosted longs threads speculating how 
try-with-resources would and would not work in practice.

We don't have to limit ourselves to speculating anymore: since there is 
a prototype which can be easily downloaded and run on many platforms, 
people can *use the feature* and report back how it works (or not) *in 
practice*.

-Joe