creating ZIP files on the cheap

[Lie Ryan]

On 12/24/2009 7:34 AM, samwyse wrote:
> I've got an app that's creating Open Office docs; if you don't know,
> these are actually ZIP files with a different extension.  In my case,
> like many other people, I generating from boilerplate, so only one
> component (content.xml) of my ZIP file will ever change.  Instead of
> creating the entire ZIP file each time, what is the cheapest way to
> accomplish my goal?  I'd kind-of like to just write the first part of
> the file as a binary blob, then write my bit, then write most of the
> table of contents as another blob, and finally write a TOC entry for
> my bit.  Has anyone ever done anything like this?  Thanks.

You might want to look at solid and non-solid compression. Solid 
compression writes all files in the binary as one huge block and must be 
compressed/decompressed as a whole, while non-solid compression writes 
the zipped file in chunks that can be decompressed individually.

I don't know if there's any way to compress/decompress/recompress as 
non-solid compression from python though. Maybe others can point 
something out, or maybe you can use an external zipper that understands 
non-solid compression.