[Python-Dev] Base-85 (original) (raw)

Josiah Carlson josiah.carlson at gmail.com
Mon Aug 11 17:59:19 CEST 2008

On Mon, Aug 11, 2008 at 8:43 AM, zooko <zooko at zooko.com> wrote:

On Aug 2, 2008, at 13:58 PM, Antoine Pitrou wrote:

Martin v. Löwis <martin v.loewis.de> writes:

P.S. Just in case it isn't clear: I would oppose any specific proposal to add this Ascii85 algorithm to the standard library. It would sound like we don't have any real problems to solve. According to Wikipedia, "its main modern use is in Adobe's PostScript and Portable Document Format file formats". ... git ... mercurial ... bzr It's sort of too bad about the April Fool's RFC, because now people tend to think that an encoding with a non-power-of-2 base is just a joke.

The best April Fool's jokes (imo) are the ones that are obviously silly right off, but that 1) work, 2) no sane person would ever use, and 3) offer up something useful hidden in the joke. The April Fool's RFC fits the bill perfectly, because out of it all comes base85, which is an actual improvement over base64 (25% expansion of data vs. 33%). That some people missed that part of the joke isn't terribly surprising (I have in other situations).

I had to overcome that when working with my programming partner, but he eventually decided that base-62 was indeed a useful encoding for our purposes. :-)

I've written a few ascii encoders over the years, mostly in Python, plus an optimized C version of base-32 (with a real live Duff's Device): base62.py: http://allmydata.org/source/z-base-62/trunk-hashedformat/z-base-62/base62/base62.py base36.py: http://allmydata.org/source/z-base-36/trunk-hashedformat/z-base-36/base36/base36.py base32.py: http://allmydata.org/source/z-base-32/trunk-hashedformat/base32/base32/base32.py base32.c: http://allmydata.org/source/z-base-32/trunk-hashedformat/base32/base32.c Regards, Zooko

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