The Daily Parker

Politics, Weather, Photography, and the Dog

Code smells

A code smell happens when a piece of software code looks like there might be something wrong with it, but you can't quite tell what. You use the smell to figure out where the bad code is hiding. Martin Fowler has devotes an entire chapter of Refactoring to code smells.

Here is an example, from a class that returns configuration information:

public string Read() { ... }

public double ReadD() { ... }

public int ReadN() { ... }

public string ReadString() { ... }

What's wrong with this code? Several things:

  1. It does the same thing four times.
  2. Having two similar methods that appear to return exactly the same data raises a red flag, because you don't know from looking at them why they differ but you feel like they differ for a reason.
  3. Despite the code's appearance, it actually offers no guarantee that the data requested will be of the correct type, only that the data will have a particular type.
  4. if some random piece of code requires a data type it doesn't support, you'll have to add yet another method to the class, or change the returned data to suit what you need, neither of which makes a lot of sense.

This code came from an ancient, functional-procedural outlook in which the type of data returned actually matters. Object-oriented design cares more about what the data represents. In other words, this code is like multiple different filler tubes on your car, one for each grade of gasoline.

There's more. A little farther on, we find these methods:

public int ReadArray(string, ref String[]) { ... }

public int ReadArray(string, ref int[]) { ... }

public int ReadIntArray(string, ref ArrayList) { ... }
	

In all, there are 14 "Readtype" methods on this class, some that return the data sought, others that return a status indication and pass the data back through a by ref parameter.

And, of course, since this is in a fundamental class, none of these methods has fewer than 5 references to it in the application, and some (like ReadN) have 34, making refactoring unusually difficult. I'll post again when I figure out how I'm going to do that.

Sunsets are getting later

In the Northern hemisphere, yesterday's was the earliest sunset of the year. Kieron Taylor, writing for the Sheffield Astronomical Society in the U.K., has a pretty good explanation of why this is so. Suffice to say, it's because the earth's orbit around the sun is elliptical.

Here, then, is a quick chart of the shortest days of the year, for Evanston, Illinois:

Date Significance Sunrise Sunset Daylight
4 Dec Earliest sunsets start 07:02 16:19 9:16
13 Dec Sunsets get later 07:10 16:20 9:09
21 Dec Solstice, 18:35 UTC 07:16 16:22 9:06
30 Dec Latest sunrises start 07:19 16:28 9:09
8 Jan Sunrises get earlier 07:18 16:37 9:18
28 Jan 5pm sunset 07:07 17:00 9:53
4 Feb 7am sunrise 07:00 17:09 10:09

You can get sunrise information for your location at wx-now.com.

Snow at rush hour

I have never, as far as I can remember, in all my years, seen a traffic report like this. I can't imagine it's accurate, showing as it does five hours from Northbrook to the Loop (a distance of 40 km, 25 mi.):

Welcome home, Danielle

As I mentioned earlier this week, my friend Danielle is returning today from Peace Corps duty in the Republic of Kiribati. For her entire tour she has lived in a place that almost never gets below 30°C (86°F). At this writing she's waiting at LAX for her flight home.

Here is what home looks like as of 15 minutes ago:

The airline claims her flight is on-time. I guess I'll find out later tonight...

Update, 3:56pm CST/21:56 UTC: The airline now reports a two-hour delay, so technically Danielle won't be getting home today.

Late update: The airline cancelled her flight after all. Still waiting...

Coat-check claim number

Yesterday at the gym's coat check, I got claim check 404.

The coat-check guy didn't find this nearly as funny as I did.

Even more funny—to a software nerd, anyway—was that when I gave him check #404 after working out, he found my coat.

One can imagine other possibilities. But 404 is the best, I think.

Hurricane season finally ends

The record-breaking 2005 hurricane season may finally be over. National Hurricane Center forecaster Avila writes this hour:

CONVECTION HAS VANISHED AND EPSILON IS NOW A TIGHT SWIRL OF LOW CLOUDS. THE CYCLONE IS WEAKENING RAPIDLY.... I HOPE THIS IS THE END OF THE LONG LASTING 2005 HURRICANE SEASON.

Good news for North Atlantic shipping, I suppose.

In Chicago, however, we have a good winter storm on its way. I'll keep you posted. Look for art around lunchtime (1:00pm CST/19:00 UTC).