Feedback and comments on ARM proposal (original) (raw)

Howard Lovatt howard.lovatt at iee.org
Wed Mar 18 17🔞48 PDT 2009

Hi All,

2009/3/19 Neal Gafter <neal at gafter.com>:

[snip]

It's not even compatible to remove a throws clause from a non-overridable method!  That's because it would break callers who invoke it in a try-catch statement.

I am not proposing to do this, I am proposing adding the new interface to existing classes if you can and if you can't then wrap the existing class in a new one. I am not proposing modifying existing interfaces at all. This is a deliberate attempt to start again with resources and provide a unified model. 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 ) ) { ... }

where

public class AutoResources { private AutoResources() {}

   public static FileAsLines asLines( final String filename )

throws FileNotFoundException { return new FileAsLines( filename ); }

   public static class FileAsLines implements AutoResource,

Iterable { private final FileReader reader;

       FileAsLines( final String filename ) throws

FileNotFoundException { reader = new FileReader( filename ); }

       public void autoDispose() {
           try { reader.close(); }
           catch ( IOException e ) { throw new IllegalStateException( e ); }
       }

      public Iterator<String> iterator() { return new

Iterator() { ... }; } }

   ...

}

(Note, in a previous post I have suggested that replacing keyword new when applied to an AutoResources with a new keyword, autoresource, this additional change would make this foreach example even clearer.)

In the above code there is no attempt to retrofit AutoResource to FileReader, instead it is wrapped.

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