General API question: returning Iterator, Iterable or even Collection?
Hi, in compress I've added a method to ZipFile that provides access to a subset of the entries. It already contained a method returning an Enumeration of all entries - Enumeration as it mimics java.util.ZipFile which was invented in Java 1.0. For this new method I've chosen to return an Iterator for now - there is no reason to use Enumeration and it seemed to be closest. In fact I first implemented it returning Iterable and changed it later. I've been doing quite a bit of .NET over the past years and there IEnumerable would have been the no-brainer choice - which translates into Iterable in Java. Lot's of .NET APIs use IEnumerable. My personal preference would be Iterable as well as the consumer may iterate over the return value multiple times without copying stuff around, but I may be missing something. There don't seem to be many APIs in the Java classlib that consume Iterators or Iterables at all. That's why I bring up Collection in the subject. Any insights or recommendations what to return? Stefan - To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
Re: General API question: returning Iterator, Iterable or even Collection?
Why not have the class implement Iterable? Gary On Jun 3, 2013, at 7:45, Stefan Bodewig bode...@apache.org wrote: Iterable - To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
Re: General API question: returning Iterator, Iterable or even Collection?
On 2013-06-03, Gary Gregory wrote: Why not have the class implement Iterable? Oh, I'm returning just a subset, so making the whole class iterable doesn't make sense. I'm talking about public IteratorZipArchiveEntry getEntries(String name) Stefan PS: For the general case of all entries this might be an option for Compress 2.x. Even then we'd still need a different method for returning entries in a different order - central directory order vs physical order. - To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
Re: General API question: returning Iterator, Iterable or even Collection?
Le 03/06/2013 13:44, Stefan Bodewig a écrit : My personal preference would be Iterable as well as the consumer may iterate over the return value multiple times without copying stuff around, but I may be missing something. I like Iterable for the ease of use in a foreach loop. But there is a risk it uses more memory than necessary. The pros for an Iterator is to be able to stream the data without holding the whole structure in memory. I don't know if that makes a real difference for your use case. An Iterable than can only be iterated once is another solution. Emmanuel Bourg - To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
Re: General API question: returning Iterator, Iterable or even Collection?
Emmanuel Bourg wrote: Le 03/06/2013 13:44, Stefan Bodewig a écrit : My personal preference would be Iterable as well as the consumer may iterate over the return value multiple times without copying stuff around, but I may be missing something. I like Iterable for the ease of use in a foreach loop. But there is a risk it uses more memory than necessary. The pros for an Iterator is to be able to stream the data without holding the whole structure in memory. I don't know if that makes a real difference for your use case. An Iterable than can only be iterated once is another solution. An Iterable returns only an Iterator, no need to keep anything in memory except of an (anonymous) Iterable instance. - Jörg - To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
Re: General API question: returning Iterator, Iterable or even Collection?
On Mon, Jun 3, 2013 at 9:15 AM, Jörg Schaible joerg.schai...@scalaris.comwrote: Emmanuel Bourg wrote: Le 03/06/2013 13:44, Stefan Bodewig a écrit : My personal preference would be Iterable as well as the consumer may iterate over the return value multiple times without copying stuff around, but I may be missing something. I like Iterable for the ease of use in a foreach loop. But there is a risk it uses more memory than necessary. The pros for an Iterator is to be able to stream the data without holding the whole structure in memory. I don't know if that makes a real difference for your use case. An Iterable than can only be iterated once is another solution. An Iterable returns only an Iterator, no need to keep anything in memory except of an (anonymous) Iterable instance. +1. I program to Iterable as often as possible. If iteration is all that is needed, then... um, it's all that is needed. ;) Matt - Jörg - To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
Re: General API question: returning Iterator, Iterable or even Collection?
On 2013-06-03, Matt Benson wrote: On Mon, Jun 3, 2013 at 9:15 AM, Jörg Schaible joerg.schai...@scalaris.comwrote: Emmanuel Bourg wrote: Le 03/06/2013 13:44, Stefan Bodewig a écrit : My personal preference would be Iterable as well as the consumer may iterate over the return value multiple times without copying stuff around, but I may be missing something. I like Iterable for the ease of use in a foreach loop. But there is a risk it uses more memory than necessary. The pros for an Iterator is to be able to stream the data without holding the whole structure in memory. I don't know if that makes a real difference for your use case. An Iterable than can only be iterated once is another solution. An Iterable returns only an Iterator, no need to keep anything in memory except of an (anonymous) Iterable instance. +1. I program to Iterable as often as possible. If iteration is all that is needed, then... um, it's all that is needed. ;) Sounds like my gut feeling of I'd prefer Iterable wasn't too far off, then. At least I'm not alone. The structure will be a list that is kept in memory anyway for the simple case and a temporary sorted version of it - most likely of length 1 - for the not-quite-so-simple case. Shouldn't make a significant difference. Thanks Stefan - To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
