Egg Timer in Python and TkInter (Shallow Thoughts)

Akkana's Musings on Open Source, Science, and Nature.

Tue, 04 Sep 2007

Egg Timer in Python and TkInter

I left the water on too long in the garden again. I keep doing that: I'll set up something where I need to check back in five minutes or fifteen minutes, then I get involved in what I'm doing and 45 minutes later, the cornbread is burnt or the garden is flooded.

When I was growing up, my mom had a little mechanical egg timer. You twist the dial to 5 minutes or whatever, and it goes tick-tick-tick and then DING! I could probably find one of those to buy (they're probably all digital now and include clocks and USB plugs and bluetooth ports) but since the problem is always that I'm getting distracted by something on the computer, why not run an app there?

Of course, you can do this with shell commands. The simple solution is:

(sleep 300; zenity --info --text="Turn off the water!") &

But the zenity dialogs are small -- what if I don't notice it? -- and besides, I have to multiply by 60 to turn a minute delay into sleep seconds. I'm lazy -- I want the computer to do that for me!
Update: Ed Davies points out that "sleep 5m" also works.

A slightly more elaborate solution is at. Say something like: at now + 15 minutes and when it prompts for commands, type something like:

export DISPLAY=:0.0
zenity --info --text="Your cornbread is ready"
to pop up a window with a message. But that's too much typing and has the same problem of the small easily-ignored dialogs. I'd really rather have a great big red window that I can't possibly miss.

Surely, I thought, someone has already written a nice egg-timer application! I tried aptitude search timer and found several apps such as gtimer, which is much more complicated than I wanted (you can define named events and choose from a list of ... never mind, I stopped reading there). I tried googling, but didn't have much luck there either (lots of Windows and web apps, no Linux apps or cross-platform scripts).

Clearly just writing the damn thing was going to be easier than finding one. (Why is it that every time I want to do something simple on a computer, I have to write it? I feel so sorry for people who don't program.)

I wanted to do it in python, but what to use for the window that pops up? I've used python-gtk in the past, but I've been meaning to check out TkInter (the gui toolkit that's kinda-sorta part of Python) and this seemed like a nice opportunity since the goal was so simple.

The resulting script: eggtimer. Call it like this:

eggtimer 5 Turn off the water
and in five minutes, it will pop up a huge red window the size of the screen with your message in big letters. (Click it or hit a key to dismiss it.)

First Impressions of TkInter

It was good to have an excuse to try TkInter and compare it with python-gtk. TkInter has been recommended as something normally installed with Python, so the user doesn't have to install anything extra. This is apparently true on Windows (and maybe on Mac), but on Ubuntu it goes the other way: I already had pygtk, because GIMP uses it, but to use TkInter I had to install python-tk.

For developing I found TkInter irritating. Most of the irritation concerned the poor documentation: there are several tutorials demonstrating very basic uses, but not much detailed documentation for answering questions like "What class is the root Tk() window and what methods does it have?" (The best I found -- which never showed up in google, but was referenced from O'Reilly's Programming Python -- was here.) In contrast, python-gtk is very well documented.

Things I couldn't do (or, at least, couldn't figure out how to do, and googling found only postings from other people wanting to do the same thing):

I expect I'll be sticking with pygtk for future projects. It's just too hard figuring things out with no documentation. But it was fun having an excuse to try something new.

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[ 13:35 Sep 04, 2007    More programming | permalink to this entry ]