Coded Smorgasbord: A Type of Insanity

Types are fundamental to most programming languages. Even the loosest, duckiest type system is still a system of some kind. It's impossible to be a programmer if you don't at least have a vague understanding of what types are, what they mean, and how you use them.

Well, not impossible.

The Null Type

Kelly came across some C# code that needed to take the value in one variable (which may be null), and store it in the property in an object. Instead of writing the obvious statement:

someObj.SomeProperty = instanceOfAClass

Kelly's predecessor wrote this:

someObj.SomeProperty = (AClass) null != null ? null : instanceOfAClass;

That conditional is a mystery: cast null to a class type, and if it somehow ceases to be null in this process, return null, otherwise return an instanceOfAClass.

The Flip Flop

That, of course, was just some copy-pasted code. Cara recently had to delve into the sewer- er, I mean plumbing- of an "enterprise" application. There, she found this pattern, copy-pasted everywhere:

String st_id = Integer.valueOf(rs.getString("student_id")).toString();msgData.setSID(Integer.parseInt(st_id));

Hey, strings everybody! Strings. And integers.

Birthyear

We usually avoid running date-related code, because dates are the easiest thing to screw up. The venerable Falsehoods Programmers Believe About Time (Part 1, Part 2) remain a great reference for all of the ways people can screw it up. But dates are a data type, so they're on theme for this article.

My personal favorite bad-date code is when they obviously know enough to use the date-related operations and functions provided by their standard library, but still mysteriously feel the need to reinvent their own at the same time. It shows knowledge without understanding. Dominique stumbled across this:

now = datetime.now()days_per_year = 365.24for age in ages: result['years'].append((now - timedelta(days=age*days_per_year)).year)

I like its attempt at handling leap years- they even recognize that the centennial years don't get leap years and drop 1/100 (of course, that only applies to centennial years divisible by 4, like 2000, but not 1900) . Of course, they're already using the .year property of the timedelta object, which is a property also mirrored on date objects- they were so close, yet so far.

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