Add DefaultMap

[GoogleCodeExporter]

Python has a swell default-assuming subclass of its Map type called
defaultdict.  It works like a regular dictionary when a value exists for a
key, but if there isn't one, it creates a value with a default factory. 
The attached patch contains a subclass of ForwardingMap called DefaultMap
that does something similar for Java Maps.  You can see some usages of
defaultdict at
http://www.python.org/doc/2.5.2/lib/defaultdict-examples.html, and all of
those are applicable to DefaultMap.

Original issue reported on code.google.com by charlie....@gmail.com on 27 Oct 2008 at 5:31

Attachments:

• google-collections_DefaultMap.diff

[GoogleCodeExporter]

Thanks for the suggestion.

Internally, Google has a caching library that includes the functionality you're
proposing. Unfortunately, that doesn't help you until we open-source it.

Original comment by jared.l....@gmail.com on 27 Oct 2008 at 5:07

• Added labels: Type-Enhancement
• Removed labels: Type-Defect

[GoogleCodeExporter]

The forthcoming snapshot will include MapMaker, which allows you to create maps 
that
do all this and more.  It should make you more than happy!

Original comment by kevin...@gmail.com on 11 Feb 2009 at 12:53

• Changed state: Fixed