Exception transparency - lone throws (no checked exceptions)

[Rémi Forax]

Paul,
this also means that you allow any method that throws a checked exception
to be called in the closure body without requiring a catch or a throws.

Rémi

Le 18/06/2010 01:37, Paul Benedict a écrit :
> Remi, I am not proposing eliminating checked exceptions. My suggestion
> is to allow the catching of checked exceptions without the compiler
> having to prove that it is going to be thrown.
>
> Example:
> try {
> // do nothing - nothing causes IOException here
> } catch (IOException e) { }
>
> That doesn't compile today. If we allowed it to compile, then checked
> exceptions could be thrown out of closures without having to be
> declared.
>
> Paul
>
> On Thu, Jun 17, 2010 at 5:58 PM, Rémi Forax<forax at univ-mlv.fr>  wrote:
>    
>> Le 18/06/2010 00:47, Stephen Colebourne a écrit :
>>      
>>> On 17 June 2010 22:52, Paul Benedict<pbenedict at apache.org>    wrote:
>>>
>>>        
>>>> My only comment is on the the "catch throws" clause.
>>>>
>>>>          
>>> ...
>>>
>>>        
>>>> Why doesn't Java relax its exception catching rules so that it's legal
>>>> to catch undeclared checked exceptions? So the compiler cannot
>>>> definitively prove the exception will be thrown, so what? It should be
>>>> backwards compatible since it is illegal today, and it takes away this
>>>> "catch throws" clause that is a bit hackish -- albeit necessary.
>>>>
>>>>          
>>> This is perfectly possible and not backwards incompatible as far as I
>>> can see (it simply makes code that wouldn't compile today start to
>>> compile.)
>>>
>>>        
>> It's possible but stupid.
>> My students must be able to write webservers and without checked exceptions,
>> it's hard to be done right. No one want a server that stop if a client
>> shutdown the connection randomly.
>>
>> Checked exception is a good way to say You must do something here to deal
>> with this uncommon case.
>>
>>      
>>> I would note that the catch side of checked exceptions is just as
>>> important as the throws side to those that favour checked. Thats why I
>>> chose the slightly less aggressive change with an additional keyword.
>>> Were this proposal to be seriously considered, I'd expect that this
>>> option would be very much on the table.
>>>
>>> Stephen
>>>
>>>        
>> Rémi
>>
>>
>>
>>