Incremental Compression

[Eyal Lotem]

Hey.

I have a problem in some network code. I want to send my packets compressed,
but I don't want to compress each packet separately (via .encode('zlib') or
such) but rather I'd like to compress it with regard to the history of the
compression stream.  If I use zlib.compressobj and flush it to get the
packet data, I cannot continue to compress with that stream.

I cannot wait until the end of the stream and then flush, because I need to
flush after every packet.

Another capability I require is to be able to copy the compression stream. 
i.e: To be able to create multiple continuations of the same compression
stream. Something like:

a = compressobj()
pre_x = a.copy()
x = a.compress('my_packet1')
# send x
# x was not acked yet, so we must send another packet via the pre_x
compressor
y = pre_x.compress('my_packet2')

Is there a compression object that can do all this?