PythonWise

Thursday, February 26, 2009

@reboot

cron has a nice special rule called @reboot which will run every time the machine is rebooted (doh!).

I use it for two main things:

Notify me when one of my servers was rebooted (sometimes IT don't tell me in advance)
Run my services. This is easier than writing an /etc/init.d scripts and I store my servers crontab in the source control, so deploying a new machine is easier.

An example:

# Notify that machine was rebooted
@reboot /path/to/mail -s "Machine $HOSTNANE rebooted" me@somewhere.com < /dev/null
# Run my server
@reboot (cd /path/to/awesome/server/directory && ./run_server)

Where run_server is usually something like:

#!/bin/bash

nohup ./server.py&

Tuesday, February 17, 2009

calc

A very simple command line/GUI calculator. The main trick here is to export all of math to the global namespace and then just eval the expression.

Thursday, February 12, 2009

twiver

A Twitter search client the updates every 10min.

#!/usr/bin/env python

from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
from urlparse import urlparse
from urllib2 import urlopen
from operator import itemgetter
from rfc822 import parsedate_tz
from time import strftime
import re
from functools import partial

try:
  import json
except ImportError:
  import simplejson as json

HTML = '''
<html>
    <head>
        <title>Twiver - Refreshing Twitter Search</title>
        <style>
            h2 {
                font-variant: small-caps;
            }
            table#results {
                border: 1px solid black;
                width: 100%;
            }
            table#results tr:hover {
                background: silver;
            }
            span#updated {
                font-family: Monospace;
            }
        </style>
    </head>
    <body>
        <h2>Twiver - Refreshing Twitter Search</h2>
        Query: <input id="query" size="60" /> <button id="run">Go</button>
        <table id="results">
        </table>
        <span id="updated"></span>
        <hr />
        By <a href="mailto:miki.tebeka@gmail.com">Miki</a>
    </body>
    <script src="jquery.js"></script>
    <script>
        var running = 0;

        function handle_result(data) {
            if (!running) {
                return;
            }

            var table = $('#results');
            table.empty();
            $.each(data, function (i, text) {
                var tr = $('<tr><td>' + text + '</td></tr>');
                table.append(tr);
            });
            $('#updated').html('Updated: ' + new Date());

            setTimeout(update, 10 * 1000);
        }

        function update() {
            var query = $.trim($('#query').val());
            url = '/search?q=' + query;
            $.getJSON(url, handle_result);
        }

        function run() {
            var button = $('#run');
            if (button.text() == "Go") {
                var query = $.trim($('#query').val());
                /* FIXME: The best way will be to disable the button until there
                  is text
                */
                if (query.length == 0) {
                    alert("Please enter *something*");
                    return;
                }
                button.text("Stop");
                running = 1;
                update();
            }
            else {
                running = 0;
                button.text("Go");
            }
        }

        function on_ready()
        {
            $('#run').click(run);
        }
        $(document).ready(on_ready);
    </script>
</html>
'''

def format_time(time):
  # Wed, 11 Feb 2009 00:10:36 +0000
  time = parsedate_tz(time)
  return strftime("%m/%d/%Y %H:%M", time[:9])

# 'http://mikitebeka.com' -> 
# '<a href="http://mikitebeka.com">http://mikitebeka.com</a>'
inject_links = partial(
  re.compile("(http://[^ ]+)").sub,
  "<a target=\"_new\" href=\"\\1\">\\1</a>")

def format_result(result):
  time = format_time(result["created_at"])
  text = inject_links(result["text"])
  return "[%s] %s" % (time, text)

class RequestHandler(BaseHTTPRequestHandler):
  def do_GET(self):
      if self.path == "/":
          self.wfile.write(HTML)
      elif self.path.startswith("/search"):
          self.updates()
      elif self.path.endswith(".js"):
          self.wfile.write(open(".%s" % self.path).read())
      else:
          self.send_error(404, "Not Found")

  def updates(self):
      o = urlparse(self.path)
      url = "http://search.twitter.com/search.json?" + o.query
      data = urlopen(url).read()
      obj = json.loads(data)
      results = map(format_result, obj["results"])
      self.wfile.write(json.dumps(results))

if __name__ == "__main__":
  server = HTTPServer(("", 8888), RequestHandler)
  server.serve_forever()

Monday, February 02, 2009

"Game of Life" in JavaScript

<html>
    <head>
        <title>Game Of Life</title>
        <style>
            table {
                border: 5px solid black;
            }
            td {
                width: 15px;
                height: 15px;
            }
            td.dead {
                background: green;
            }
            td.alive {
                background: red;
            }
        </style>
    </head>
    <body>
        <b>Game of Life<b>
        <table id="board">
        </table>
        <button id="run">Run</button>
        <button id="step">Step</button>
        <button id="clear">Clear</button>

    </body>
    <script src="jquery.js"></script>
    <script>
        var NUM_ROWS = 30;
        var NUM_COLS = 30;
        var DEAD = 'dead';
        var ALIVE = 'alive';
        var RUNNING = 0;
        /* We keep this for fast access since jQuery selectors
        $('#board tr:nth-child(' + row + 1 + ') td:nth-child(' + col + 1 + ')'
        are slow
        */
        var BOARD = [];

        function copy_board() {
            var board = [];
            for (var row = 0; row < NUM_ROWS; ++row) {
                var cells = [];
                for (col = 0; col < NUM_COLS; ++col) {
                    var state = get_cell(row, col).hasClass(ALIVE) ?
                                ALIVE : DEAD;
                    cells.push(state);
                }
                board.push(cells);
            }

            return board;
        }

        function cell_neighbours(row, col) {
            var uprow = (row + 1) % NUM_ROWS;
            var downrow = (row - 1) % NUM_ROWS;
            var leftcol = (col - 1) % NUM_COLS;
            var rightcol = (col + 1) % NUM_COLS;

            /* FIXME: Find a better way (since -1 % 10 => -1) */
            downrow = (downrow < 0) ? NUM_ROWS - 1 : downrow;
            leftcol = (leftcol < 0) ? NUM_COLS - 1 : leftcol;

            return [
                [uprow, leftcol], [uprow, col], [uprow, rightcol],
                [row, leftcol], [row, rightcol],
                [downrow, leftcol], [downrow, col], [downrow, rightcol]
            ];
        }

        /* http://en.wikipedia.org/wiki/Conway%27s_Game_of_Life#Rules */
        function calc_new_state(current_state, num_alive) {
            if (current_state == ALIVE) {
                if (num_alive < 2) {
                    return DEAD;
                }
                else if (num_alive > 3) {
                    return DEAD;
                }
                else {
                    return ALIVE;
                }
            }
            else {
                if (num_alive == 3) {
                    return ALIVE;
                }
                else {
                    return DEAD;
                }
            }
        }


        function on_step() {
            /* Copy old board since we're going to change the current */
            var board = copy_board();

            function is_alive(cell) {
                return board[cell[0]][cell[1]] == ALIVE;
            }

            for (var row = 0; row < NUM_ROWS; ++row) {
                for (var col = 0; col < NUM_COLS; ++col) {
                    var neighbours = cell_neighbours(row, col);
                    var num_alive = $.grep(neighbours, is_alive).length;
                    var current_state = board[row][col];
                    var new_state = calc_new_state(current_state, num_alive);
                    if (new_state != current_state) {
                        toggle(row, col);
                    }
                }
            }
        }

        function run() {
            if (!RUNNING) {
                return;
            }
            on_step();
            setTimeout(run, 200);
        }

        function on_run() {
            var button = $('#run');
            if (button.text() == 'Run') {
                button.text('Stop');
                RUNNING = 1;
                run();
            }
            else {
                button.text('Run');
                RUNNING = 0;
            }
        }

        function get_cell(row, col) {
            return BOARD[row][col];
        }

        function toggle(row, col) {
            var cell = get_cell(row, col);

            if (cell.hasClass(ALIVE)) {
                var add = DEAD;
                var remove = ALIVE;
            }
            else {
                var add = ALIVE;
                var remove = DEAD;
            }

            cell.removeClass(remove).addClass(add);
        }

        function make_handler(row, col) {
            return function() {
                toggle(row, col);
            }
        }

        function initiaize_board() {
            var table = $('#board');
            for (var row = 0; row < NUM_ROWS; ++row) {
                var tr = $('<tr />');
                var cells = [];
                for (var col = 0; col < NUM_COLS; ++col) {
                    var td = $('<td />');
                    td.addClass(DEAD);
                    td.click(make_handler(row, col));
                    tr.append(td);
                    cells.push(td);
                }
                table.append(tr);
                BOARD.push(cells);
            }
        }

        function on_clear() {
            $('.' + ALIVE).removeClass(ALIVE).addClass(DEAD);
        }

        function on_ready()
        {
            initiaize_board();
            $('#step').click(on_step);
            $('#run').click(on_run);
            $('#clear').click(on_clear);
        }

        $(document).ready(on_ready);
    </script>
</html>

Wednesday, January 28, 2009

Find Module Version

Quick script to check which version of Python module is installed.

#!/usr/bin/env python
'''Find python module version'''

__author__ = "Miki Tebeka <miki.tebeka@gmail.com>"

def valueof(v):
    if callable(v):
        try:
            return v()
        except Exception:
            return None
    return v

def load_module(module_name):
    module = __import__(module_name)

    # __import__("a.b") will give us a
    if ("." in module_name):
        names = module_name.split(".")[1:]
        while names:
            name = names.pop(0)
            module = getattr(module, name)

    return module

def find_module_version(module_name):
    module = load_module(module_name)
    attrs = set(dir(module))

    for known in ("__version__", "version", "version_string"):
        if known in attrs:
            v = valueof(getattr(module, known))
            if v:
                return v

    for attr in attrs:
        if "version" in attr.lower():
            v = getattr(module, attr)
            if not v:
                continue
            v = valueof(v)
            if v:
                return v

def main(argv=None):
    if argv is None:
        import sys
        argv = sys.argv

    from optparse import OptionParser

    parser = OptionParser("usage: %prog MODULE_NAME")

    opts, args = parser.parse_args(argv[1:])
    if len(args) != 1:
        parser.error("wrong number of arguments") # Will exit

    module_name = args[0]

    try:
        version = find_module_version(module_name)
    except ImportError, e:
        raise SystemExit("error: can't import %s (%s)" % (module_name, e))

    if version:
        print version
    else:
        raise SystemExit("error: can't find version for %s" % module_name)

if __name__ == "__main__":
    main()

Friday, January 16, 2009

Which build utility to run?

I have the following as a script called "mk" and set in my .vimrc

set makeprg=mk

#!/bin/bash
# Guess which make utility to use

# Miki Tebeka <miki.tebeka@gmail.com>

makecmd=""
if [ -f SConstruct ]; then
    makecmd="scons -Q -D"
elif [ -f build.xml ]; then
    makecmd="ant"
elif [ -f Makefile ]; then
    makecmd="make"
elif [ -f makefile ]; then
    makecmd="make"
elif [ "$OSTYPE" == "WINNT" ]; then
    proj=`ls *.dsp 2>/dev/null`
    if [ -f $proj ]; then
        makecmd="msdev $proj /MAKE"
    fi
fi

if [ -z "$makecmd" ]; then
    echo "can't find project file"
    exit 1
fi

$makecmd $@

Wednesday, January 07, 2009

Moved to bitbucket

All(?) the code from this blog is now at BitBucket

Friday, December 12, 2008

crashlog

Get email notification whenever your program crashes.

Friday, November 14, 2008

The Code You Don't Write


Act without doing, work without effort.
Think of the small as large and the few as many.
Confront the difficult while it is still easy;
accomplish the great task by a series of small steps.
    - Lao-Tze

Sometimes, the code you don't write is more important than the one you write.
Whenever I start on a new task, my first question is "how can I do this without coding?".

Here's a small (true) exmaple:

We had a problem that serving files on an NFS mounted volume was slow for the first request and them it was good. Probably the mount went "stale" after a while.

First option of learning the inner working of NFS mounts was dropped immediately - you can never know how much time this tinkering will take and if it'll work eventually.

So I decided to keep the NFS mount "warm" by periodically accessing it.

First Version:

from time import sleep
from os import listdir

while 1:
    listdir("/path/to/nfs")
    sleep(10 * 60 * 60)

and in crontab


@reboot /usr/bin/python /path/to/script.py

Then I thought - "cron", and second version came:

from os import listdir

listdir("/path/to/nfs")</code></pre>

and in crontab:


*/10 * * * * /usr/bin/python /path/to/script.py

And then last version (just crontab):


*/10 * * * * /bin/ls /path/to/nfs

So down from 6 LOC to 3 LOC to 1 LOC - that's what I call produtivity :)

Saturday, November 08, 2008

Where is Miki?

A little CGI script that show where I am (gets data from my google calendar).

Using Google Data Python API

#!/usr/bin/env python
'''Where where am I? (data from Google calendar)

Get gdata from http://code.google.com/p/gdata-python-client/
'''

__author__ = "Miki Tebeka <miki.tebeka@gmail.com>"

import gdata.calendar.service as cal_service
from time import localtime, strptime, strftime, mktime, timezone

DAY = 24 * 60 * 60

def caltime_to_local(caltime):
    # 2008-11-07T23:30:00.000+02:00
    t = mktime(strptime(caltime[:16], "%Y-%m-%dT%H:%M"))
    tz_h, tz_m = map(int, caltime[-5:].split(":"))
    cal_tz = (tz_h * 60 * 60) + (tz_m * 60)
    if caltime[-6] == "-":
        cal_tz = -cal_tz

    # See timezone documentation, the sign is reversed
    diff = -timezone - cal_tz 

    return localtime(t + diff)

def iter_meetings():
    client = cal_service.CalendarService()
    client.email = "your-google-user-name"
    client.password = "your-google-password"
    client.source = "Where-is-Miki"
    client.ProgrammaticLogin()

    query = cal_service.CalendarEventQuery("default", "private", "full")
    query.start_min = strftime("%Y-%m-%d")
    tomorrow = localtime(mktime(localtime()) + DAY)
    query.start_max = strftime("%Y-%m-%d", tomorrow)
    feed = client.CalendarQuery(query)
    for event in feed.entry:
        title = event.title.text
        when = event.when[0]
        start = caltime_to_local(when.start_time)
        end = caltime_to_local(when.end_time)

        yield title, start, end

def find_meeting(meetings, now):
    for title, start, end in meetings:
        print title, start, end
        if start <= now <= end:
            return title, end

    return None, None

def meetings_html(meetings):
    if not meetings:
        return "No meetings today"

    trs = []
    tr = "<tr><td>%s</td><td>%s</td><td>%s</td></tr>"
    for title, start, end in meetings:
        start = strftime("%H:%M", start)
        end = strftime("%H:%M", end)
        trs.append(tr % (title, start, end))

    return "Today's meetings: <table border='1'>" + \
           "<tr><th>Title</th><th>Start</th><th>End</th></tr>" + \
            "\n".join(trs) + \
            "</table>"

HTML = '''
<html>
    <head>
        <title>Where is Miki?</title>
        <style>
            body, td, th {
                font-family: Monospace;
                font-size: 22px;
            }
        </style>
    </head>
    <body>
        <h1>Where is Miki?</h1>
        <p>
            Seems that he is <b>%s</b>.
        </p>
        <p>
            %s
        </p>
    </body>
</html>
'''

if __name__ == "__main__":
    import cgitb; cgitb.enable()
    from operator import itemgetter

    days = ["Mon","Tue","Wed", "Thu", "Fri", "Sat", "Sun"]
    now = localtime()

    day = days[now.tm_wday]
    meetings = sorted(iter_meetings(), key=itemgetter(-1))

    # Yeah, yeah - I get in early
    if (now.tm_hour < 6) or (now.tm_hour > 17):
        where = "at home"
    elif day in ["Sat", "Sun"]:
        where = "at home"
    else:
        title, end = find_meeting(now, meetings)
        if end:
            where = "meeting %s (until %s)" % (title, strftime("%H:%M", end))
        else:
            where = "at work"

    print "Content-Type: text/html\n"
    print HTML % (where, meetings_html(meetings))

Wednesday, November 05, 2008

Document With Examples

I've found out that a lot of times when I have a parsing code, it's best to document the methods with examples of the input.

A small example:

#!/usr/bin/env python
'''Simple script showing how to document with examples'''

__author__ = "Miki Tebeka <miki.tebeka@gmail.com>"

import re

# HTTP/1.1 200 OK
# HTTP/1.1 301 Moved Permanently
def http_code(line):
    return line.split()[1]

if __name__ == "__main__":
    print http_code("HTTP/1.1 301 Moved Permanently")

Monday, October 13, 2008

JavaScript sound player

It's very easy to connect Adobe FLEX to JavaScript.

We'll create a simple sound player that exposes two functions: play and stop. It'll also call the JavaScript function on_play_complete when the current sound has finished playing.

soundplayer.mxml

Compile with mxmlc soundplayer.mxml

soundplayer.html

Tuesday, September 23, 2008

"Disabling" an image

Sometimes you want to mark a button image as "disabled". The usual method is to have two images and display the "disabled" state image when disabled.

However you can use the image opacity the mark is as disabled as well:


<html>
    <head>
        <title>Dimmer</title>
        <style>
            .disabled {
                filter: alpha(opacity=50);
                -moz-opacity: 0.50;
                opacity: 0.50;
            }
        </style>
    </head>
    <body>
        <center>
            <p>Show how to "dim" an image, marking it disabled</p>
            <img src="image.png" id="image" /> <br />
            <button onclick="disable();">Disable</button>
            <button onclick="enable();">Enable</button>
        </center>
    </body>
    <script src="jquery.js"></script>
    <script>
        function disable() {
            $('#image').addClass('disabled');
        }

        function enable() {
            $('#image').removeClass('disabled');
        }
    </script>
</html>

Thursday, September 18, 2008

Destktop Web Application

It's very easy have the browser window as your user interface, even on desktop applications.

Below is a small phone book demo.

General Design:

Have a web server serve the main search page

I'm using BaseHTTPServer but you can use any other framework

Run an AJAX query and display the results

I'm using jQuery

fork the server so the program will return

webphone.py (AKA the web server)

index.html (AKA the GUI)

pymodver

Which version of module do I have?

#!/usr/bin/env python
'''Find python module version'''

__author__ = "Miki Tebeka <miki.tebeka@gmail.com>"

def valueof(v):
    if callable(v):
        try:
            return v()
        except Exception:
            return None
    return v

def load_module(module_name):
    module = __import__(module_name)

    # __import__("a.b") will give us a
    if ("." in module_name):
        names = module_name.split(".")[1:]
        while names:
            name = names.pop(0)
            module = getattr(module, name)

    return module

def find_module_version(module_name):
    module = load_module(module_name)
    attrs = set(dir(module))

    for known in ("__version__", "version"):
        if known in attrs:
            v = valueof(getattr(module, known))
            if v:
                return v

    for attr in attrs:
        if "version" in attr.lower():
            v = getattr(module, attr)
            if not v:
                continue
            v = valueof(v)
            if v:
                return v

def main(argv=None):
    if argv is None:
        import sys
        argv = sys.argv

    from optparse import OptionParser

    parser = OptionParser("usage: %prog MODULE_NAME")

    opts, args = parser.parse_args(argv[1:])
    if len(args) != 1:
        parser.error("wrong number of arguments") # Will exit

    module_name = args[0]

    try:
        version = find_module_version(module_name)
    except ImportError, e:
        raise SystemExit("error: can't import %s (%s)" % (module_name, e))

    if version:
        print version
    else:
        raise SystemExit("error: can't find version for %s" % module_name)

if __name__ == "__main__":
    main()

Tuesday, September 16, 2008

Exit Gracefully

When your program is terminated by a signal, the atexit handlers are not called.

A short solution:

Sunday, September 07, 2008

"unpack" updated

Updated the code to unpack and added view functionality to it.

Thursday, September 04, 2008

putclip

A "cross platform" command line utility to place things in the clipboard.
(On linux uses xsel)

#!/usr/bin/env python
'''Place stuff in clipboard - multi platform'''

__author__ = "Miki Tebeka <miki.tebeka@gmail.com>"

from os import popen
from sys import platform

COMMDANDS = { # platform -> command
    "darwin" : "pbcopy",
    "linux2" : "xsel -i",
    "cygwin" : "/bin/putclip",
}

def putclip(text):
    command = COMMDANDS[platform]
    popen(command, "w").write(text)

def main(argv=None):
    if argv is None:
        import sys
        argv = sys.argv

    from optparse import OptionParser
    from sys import stdin

    parser = OptionParser("%prog [PATH]")

    opts, args = parser.parse_args(argv[1:])

    if len(args) not in (0, 1):
        parser.error("wrong number of arguments") # Will exit

    if platform not in COMMDANDS:
        message = "error: don't know how to handle clipboard on %s" % platform
        raise SystemExit(message)

    if (not args) or (args[0] == "-"):
        info = stdin
    else:
        try:
            infile = args[0]
            info = open(infile)
        except IOError, e:
            raise SystemExit("error: can't open %s - %s" % (infile, e))

    try:
        putclip(info.read())
    except OSError, e:
        raise SystemExit("error: %s" % e)

if __name__ == "__main__":
    main()

Friday, August 15, 2008

flatten


#!/usr/bin/env python

__author__ = "Miki Tebeka <miki.tebeka@gmail.com>"

def flatten(items):
    '''Flatten a nested list.

    >>> a = [[1], 2, [[[3]], 4]]
    >>> list(flatten(a))
    [1, 2, 3, 4]
    >>>
    '''
    for item in items:
        if getattr(item, "__iter__", None):
            for subitem in flatten(item):
                yield subitem
        else:
            yield item

if __name__ == "__main__":
    from doctest import testmod
    testmod()