Hi Derek, On 2/16/07, Derek Shockey <derek.shockey@gmail.com> wrote:
Though I am an avid Python programmer, I've never forayed into the area of developing Python itself, so I'm not exactly sure how all this works.
I was confused (and somewhat disturbed) to discover recently that the zipfile module offers only one-shot decompression of files, accessible only via the read() method. It is my understanding that the module will handle files of up to 4 GB in size, and the idea of decompressing 4 GB directly into memory makes me a little queasy. Other related modules (zlib, tarfile, gzip, bzip2) all offer sequential decompression, but this does not seem to be the case for zipfile (even though the underlying zlib makes it easy to do).
Not so easy, in fact. Unless you open only one zip member file at a time. If you open many member files concurrently how does file cache will work? Or how many seeks you will have to do if you read from one member file and from other alternatingly? Do you have a file-like interface or just read in chunks? Or, if you need to open more than one member file for writing in the same zip file, then this is not possible at all.
Since I was writing a script to work with potentially very large zipped files, I took it upon myself to write an extract() method for zipfile, which is essentially an adaption of the read() method modeled after tarfile's extract(). I feel that this is something that should really be provided in the zipfile module to make it more usable. I'm wondering if this has been discussed before, or if anyone has ever viewed this as a problem. I can post the code I wrote as a patch, though I'm not sure if my file IO handling is as robust as it needs to be for the stdlib. I'd appreciate any insight into the issue or direction on where I might proceed from here so as to fix what I see as a significant problem.
My Google Summer of Code project was just about this, and I implemented a lot of nice features. These features include: file-like access to zip member files (which solves your problem, and also provides a real file-like interface including .read(), .readline(), etc); support for BZIP2 compression; support for removing a member file; support for encrypting/decrypting member files. The project is hosted at sourceforge [http://ziparchive.sf.net]. You can take a look, and try it. I'm planning to make a new and improved release perfecting the API and doing some code refactoring. I really think that this improved version will be better than all other zip libraries in every aspect, including number of implemented features, speed/efficiency, and being easy to use. I think the time I will take to do this is roughly directly proportional to the amount of feedback (and help) I receive, since I alone can't think about all the needs of such a library. Also, if anyone would like to help developing, that you be great! I have some local code I'm working in, but I can commit this to an svn branch if anyone would like to see/help. Thanks, -- Nilton