Snakes on an Apple!

Blake Winton

As I mentioned before, we got a Mac Mini. It's been a bit of a pain getting it all set up, but I think we're finally done. The web server is moved over, along with all the websites. The mail server is moved over, and I took the opportunity to delete my mother's account. (That's not as bad as it sounds. She had it redirecting to GMail anyways, and the error message says as much. Of course, since I haven't told her about it yet, this will probably come as a bit of a surprise.) Uh, and that turned out to be all the servers I was running. Well, I was running CherryPy, and some other stuff, but it wasn't particularly important, and I've found better ways of doing it, for the most part.

But that's not really why I'm posting here. I'm posting here because I got some cool Python stuff working under the Mac, and I wanted to share it. Specifically, I (or rather, my wife and I) wanted to have a window showing on the login screen, displaying the weather. After several bits of trial and error, and liberal "borrowing" from Dethe Elza's Pastels project I finally got something which would do what I wanted. First, the code:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
 
from AppKit import NSObject, NSApplication, NSTimer, NSApp, NSURL
from AppKit import NSURLRequest, NSWindow, NSTitledWindowMask
from AppKit import NSClosableWindowMask, NSMiniaturizableWindowMask
from AppKit import NSResizableWindowMask, NSBackingStoreBuffered
from BeautifulSoup import BeautifulSoup
from PyObjCTools import AppHelper
from WebKit import WebView, WebDataSource

import os
import stat
import time
import urllib

width, height = 620, 540

def Window(title, width, height, view=None):
    window = NSWindow.alloc().initWithContentRect_styleMask_backing_defer_(
        ((0,0),(width,height)),
        NSTitledWindowMask |
        NSClosableWindowMask | 
        NSMiniaturizableWindowMask |
        NSResizableWindowMask,
        NSBackingStoreBuffered,
        False)
    window.setTitle_(title)
    if view:
        window.setContentView_(view)
    window.orderFront_(window)
    return window

class MyAppDelegate(NSObject):
    def update( self, timer ):
        y = urllib.urlopen( str(self.wUrl) ).read()
        b = BeautifulSoup( y )
        self.view.mainFrame().loadHTMLString_baseURL_(
            """<html><head><title>test<title>%s<head>
            <body>%s<body><html>""" %
            ("".join( [str(x) for x in b.head.findAll( 'style' )]), b.body.div.div.div.div.div),
            self.wUrl )

    def applicationDidFinishLaunching_(self, notification):
        rect = ((0,0),(width, height))
        self.view = WebView.alloc().initWithFrame_(rect)
        self.window = Window('Pastels Test', width, height, self.view)
        self.window_delegate = MyWindowDelegate.alloc().init()
        self.window.setDelegate_(self.window_delegate)
        self.wUrl = NSURL.alloc().initWithString_(
            "http://weatheroffice.ec.gc.ca/city/pages/on-143_metric_e.html")
        self.update( None )
        timer = NSTimer.scheduledTimerWithTimeInterval_target_selector_userInfo_repeats_(
            1800, self, 'update', None, True )

class MyWindowDelegate(NSObject):
    def windowWillClose_(self, notification):
        NSApp().terminate_(self)

def main():
    app_delegate = MyAppDelegate.alloc().init()
    NSApplication.sharedApplication().setDelegate_(app_delegate)   
    AppHelper.runEventLoop(installInterrupt=True)


if __name__ == "__main__":
    while True:
        if os.stat( "/dev/console" )[stat.ST_UID] == 0:
            # If the console is owned by root, start the app.
            main()
        else:
            # Otherwise, sleep until it is.
            time.sleep( 10 )


And next, the launchd plist file that keeps it running:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
 
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
"http://www.apple.
com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>  
    <key>Label</key>
    <string>ca.latte.update.login.weather</string>
    <key>ProgramArguments</key>
    <array> 
        <string>/path/to/test.py</string>
    </array>
    <key>ServiceDescription</key>
    <string>A program to pop up the weather in a box</string>
    <key>LowPriorityIO</key>
    <true/>
    <key>RunAtLoad</key>
    <true/>
    <key>OnDemand</key>
    <false/>
    <key>Nice</key>
    <integer>1</integer>
    <key>StandardOutPath</key>
    <string>/path/to/loginWeather.out</string>
    <key>StandardErrorPath</key>
    <string>/path/to/loginWeather.err</string>
</dict>
</plist>

And there you have it. Way cooler than my previous attempt, which tried to write using sudo defaults write /Library/Preferences/com.apple.loginwindow LoginwindowText -string "parsed weather info here".

If any of you have any questions, I'ld love to answer them as best I can. Just comment, and I'll see what I can dig up. By which I mean email Dethe, and ask him. ;)