Aaron Maenpaa

Extensions

I make pretty heavy use of both the Mercurial Queues and Rebase extensions. In tandem, they give me the ability to make my changesets to be exactly what I want them to be and to move my local branches to tip before I push (which I use so that I don't have to add trivial merge changesets). My workflow has a tendecy to look like this:

$ # do work
$ hg qnew -f -m "A pithy commit message bugzid: 1234567" a_patch.diff
$ hg qpush -a
applying first.diff
now at: first.diff
$ hg pull --rebase
pulling from /a/repository
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
$ hg qpop
popping first.diff
now at: a_patch.diff
$ hg qfinish -a
$ hg push
pushing to /a/repository
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
$ hg qpush
applying first.diff
now at: first.diff
$ # do more work
$ hg qrefresh
$ hg pull --rebase
pulling from /a/repository
searching for changes
no changes found
$ hg qfinish -a
$ hg push
pushing to /a/repository
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files

Sure, I could live in the world of hg fetch and type fewer commands, but I feel like having nice atomic changesets, commit messages without typos and a nice clean history is worth the extra typing.

And the winner is...

The big change is that Mercurial has completely replaced Subversion as my version control system of choice. Not only that, but I actually use hg more than I used to use svn. Part of this is that hg is better/faster/easier/more useful than svn and part of it is that I've really gotten in the habit of using Mercurial for everything (which you might argue is a consequence of that first thing ;-).

I've started using Paver and Fabric and they are both awesome. I've stopped using Rails, but I was only really using it for school (My current "web framework" of choice is CherryPy, it is also awesome).

./blogc which takes the number four sport, is one of the new tools that I use to work on my blog.

Other than that, I still use gvim, rm, ls, and cd. Shocking!

Teh Codez

It occurred to me that it should be pretty straightforward to build a web app that implemented the Gravatar API and desaturate real Gravatars, so I took a crack at it:

import StringIO
import urllib, urllib2

import cherrypy
import Image

from paver.easy import path

URL = "http://www.gravatar.com/avatar/%s?%s"

class Grayvatar(object):
    @cherrypy.expose
    def default(self, *bits, **kwargs):
        if bits:
            cherrypy.response.headers["Content-Type"] = "image/png"
            url = URL % (bits[0], urllib.urlencode(kwargs))
            img = get_img(url).convert("L")
            return img_as_str(img)

        pwd = path(__file__).abspath().parent
        return (pwd / "how_it_works.html").text()

def get_img(url):
    sock = urllib2.urlopen(url)
    return Image.open(StringIO.StringIO(sock.read()))

def img_as_str(img):
    sock = StringIO.StringIO()
    img.save(sock, "png")
    return sock.getvalue()

if __name__ == "__main__":
    cherrypy.quickstart(Grayvatar())

I think it's awesome that, thanks to CherrPy and PIL, I could put together a web app that does all that 30 odd lines (including imports), but it's less awesome that so many of those lines are shuffling data in and out of a StringIO.

mod_wsgi

I set up an instance at: http://aaron.maenpaa.ca/grayvatar using Apache and mod_wsgi. I used a lightly adapted version of the the wsgi config from the CherryPy wiki.

import sys
sys.stdout = sys.stderr

import atexit
import threading
import cherrypy

sys.path = ['/home/aaron/code/grayvatar'] + sys.path

import grayvatar

cherrypy.config.update({
    'environment': 'embedded',
    'log.screen': True,
})

if cherrypy.__version__.startswith('3.0') and cherrypy.engine.state == 0:
    cherrypy.engine.start(blocking=False)
    atexit.register(cherrypy.engine.stop)

application = cherrypy.Application(grayvatar.Grayvatar(), script_name=None)

The most important change was adding 'log.screen': True to the config. This sends errors to stderr, which eventually makes it's way to /var/log/apache2/error.log which makes it possible to figure out what's going on when things don't go right.

How It Works

Just like Gravatar. The base URL is http://aaron.maenpaa.ca/grayvatar/. You calculate the MD5 hash of your email address, append it to the base URL and then add any query parameters that Gravatar supports. That gets you a URL like this: http://aaron.maenpaa.ca/grayvatar/634329486bd326c395c8b3539c035139?s=256&d=identicon&r=PG

It fetchs the appropriate Gravatar, desaturates and returns it. Keep in mind, this is a toy: It doesn't actually respect the cache headers Gravatar sends and worse, it doesn't even pass them along to the client.