CloseableStream exceptions [was: Re: experience trying out lambda-8-b74]

[Alan Bateman]

On 04/02/2013 19:02, Peter Levart wrote:
>
> I think that every new API or feature takes some time to get used. When
> try-with-resources was introduced, nobody was thinking to use it just
> because of java.io methods throwing checked IOException. I aggree that
> now many programmers mentally associate IOException with
> try-with-resources and you want to piggy-back on that mental perception.
> You might get quick response at the beginning, but for the price of
> long-term ugliness of exception handling when using the API. I expect
> people would be asking for another factory method throwing
> UncheckedIOException in JDK9 after the API is going to get used massively...
>
All methods to open or access files, directories, etc. in this API throw 
the checked IOException. It would be inconsistent to introduce a 
parallel set of methods at this point, particularly because this API 
also defines also many specific IOExceptions for cases where recovery 
might be required for specific cases.

So I think if CloseableStream is used in a try-with-resources that opens 
the file or directory then it will probably lead to usages such as:

try (...) {
      :
} catch (UncheckedIOException e) {
     throw e.getCause();
}

or

try (...) {
     :
} catch (IOException ioe) {
     throw new UncheckedIOException(ioe);
}

depending on whether you want to propagate a checked or unchecked 
exception. One of two examples in the javadoc might help.

-Alan.