After my last post regarding FS, my file-system abstraction layer for Python, I think I may have left people thinking,"that's nice, but what would you use if for?". Generally, I see it as a way of simplifying file access and exposing only the files you need for your application -- regardless of their physical source. But I can think of a few other uses that may be a littler cooler.
Instant Archive Format
The osfs.MemoryFS class is a filesytem that exists only in memory. You can create files / directories and copy files to it from other filesystem objects, but when you open a file you will get back a StringIO object (from the standard library). Naturaly the files in a MemoryFS are transitory, but as everything is in memory, file access is very fast. I was thinking that since the files and directories are stored as simple Python objects, then a MemoryFS can be pickled -- creating an instant archive format. Uncompressing this archive would simply require unpicking and using the resultant object. I can't see any advantages of this over zip or tar archives, but if you don't have them available, this would be a workable substitute!
It wouldn't be particularly challenging to write an FS an object that created a filesystem on a database. Actualy, if using an ORM like SQLAlchemy, SQLObject, Storm or Django's database layer it would be fairly trivial. So what would you use such a thing for? I can think of one use which may make it worth the effort, and that is the ability to store templates for a Python web application in the database, rather than (or in addition to) files. Consider if you will, a situation where the client has requested a change that is absolutely critical to the success of his company and he won't take "it will be in the next release" for an answer, and neither will your project manager. Wouldn't it be nice if you could go in to the Django admin pages and just type in the changes, without making a new release. I'm tempted to implement such a thing, if nobody has done so already!
Proxying a Filesystem
A generic filesystem server could be written that exposes a remote file-system over whatever channel is available. I know there are some standard ways of doing this, but they might not be available on a given platform. I'm thinking of small devices with limited capabilities, or secure environments. The server would serve an FS object, and the client would present the app with a corresponding interface that pulled files and directories over the wire.
There you go. If anyone implements these, let me know!