Feedback and comments on ARM proposal - resend

[Neal Gafter]

On Wed, Mar 18, 2009 at 5:18 PM, Howard Lovatt <howard.lovatt at iee.org> wrote:
> For example suppose as Neal has suggested
> that the foreach loop understood resources, it would be great to write
> something like:
>
>    for ( final String line : AutoResources.asLines( filename ) ) { ... }

Howard-

I think you may have missed my point.  It isn't the Iterable that the
for-each loop needs to handle as a resource, because the programmer
can easily do that himself

try (final AutoResource linesInFile = AutoResources.asLines(filename)) {
  for ( String line : linesInFile ) {
    ...
  }
}

Rather, I'm talking about the implicit Iterator variable that is
created by the expansion of the for-each loop.  Unlike Iterable,
Iterators are one-shot, so making one a resource is natural.  But,
with the current ARM proposal, there is no way to use the for-each
loop with an Iterable whose Iterator is an AutoResource.  Experience
with C#'s foreach loop and IDisposable/IEnumerable has shown the
combination to be very useful, as it avoids some very awkward
situations when both resources and loops are used together in a
program.

These kinds of issues make me think that more actual experience with
the proposed construct will be required before we can have confidence
that it is "right".

Regards,
Neal