try-with-resources and null resource

[Tim Peierls]

On Mon, Jan 24, 2011 at 6:49 PM, Rémi Forax <forax at univ-mlv.fr> wrote:

> > Those who don't want it don't have it forced on them. If the null check
> were
> > always performed, I'd have no way to use try-with-resources *and* get the
> > side-effects of executing the body up to the point where the null
> Resource
> > is dereferenced.
>
> side-effects => hours of debugging
>

Maybe, but once it's debugged you don't want those side-effects to disappear
because of magical null checks.



> > (Not saying one always wants to do this, or even that one
> > often wants to do this, just that try-with-resources shouldn't prevent
> it.)
>
> Do you have a use case for that ?
>

Burden of proof goes the other way: There's a lot of existing code out there
that could be rewritten to use try-with-resources, and I'd to have to bet
that none of it would be better off waiting until the first attempt to
dereference to throw NPE.



> And even if you find a twisted use case, do you really think anyone will be
> able to understand that code ?
>

The harder the code is to understand, the more important it is not to risk
changing its behavior through over-protectiveness.

If you want a null check at initialization, add it -- it's 14 characters if
you use Guava. You can claim that you'll always want to check early, but you
can't dictate that no one else should ever want to defer the check.

--tim