I was reading on Stackoverflow.com (the beta version) about useful articles in a programmer's career. I stumbled upon the following pearl :

How To Write Unmaintainable Code by Roedy Green.

A very well written counter-example, well structured. An excellent combination of humor and discipline. I strongly recommend readin the original article, using the link above. However if none of these don't convince you I will show a few samples here :

 

In the interests of creating employment opportunities in the Java programming field, I am passing on these tips from the masters on how to write code that is so difficult to maintain, that the people who come after you will take years to make even the simplest changes. Further, if you follow all these rules religiously, you will even guarantee yourself a lifetime of employment, since no one but you has a hope in hell of maintaining the code. Then again, if you followed all these rules religiously, even you wouldn’t be able to maintain the code!

Let's get started :

Be Abstract

In naming functions and variables, make heavy use of abstract words like it, everything, data, handle, stuff, do, routine, perform and the digits e.g. routineX48, PerformDataFunction, DoIt, HandleStuff and do_args_method.

Abstract notions :

Programmers are lulled into complacency by conventions. By every once in a while, by subtly violating convention, you force him to read every line of your code with a magnifying glass.

You might get the idea that every language feature makes code unmaintainable — not so, only if properly misused.

Naming conventions seem to be a mantra :

Bedazzling Names

Choose variable names with irrelevant emotional connotation. e.g.:

marypoppins = (superman + starship) / god;

This confuses the reader because they have difficulty disassociating the emotional connotations of the words from the logic they’re trying to think about.

Reuse of Global Names as Private

Declare a global array in module A, and a private one of the same name in the header file for module B, so that it appears that it’s the global array you are using in module B, but it isn’t. Make no reference in the comments to this duplication.

Something that I thought people should go to jail for :

Overload new

Overload the “new” operator - much more dangerous than overloading the +-/*. This can cause total havoc if overloaded to do something different from it’s original function (but vital to the object’s function so it’s very difficult to change). This should ensure users trying to create a dynamic instance get really stumped. You can combine this with the case sensitivity trickalso have a member function, and variable called “New”.

A timeless pearl :

Clone & Modify

In the name of efficiency, use cut/paste/clone/modify. This works much faster than using many small reusable modules. This is especially useful in shops that measure your progress by the number of lines of code you’ve written.

Unheard horrors :

Use Three Dimensional Arrays

Lots of them. Move data between the arrays in convoluted ways, say, filling the columns in arrayB with the rows from arrayA. Doing it with an offset of 1, for no apparent reason, is a nice touch. Makes the maintenance programmer nervous.

If by now you are not convinced that this is an article worth reading I assure you the samples shown by me here don't cover more than 10% of the material there.

 

Go read it !!!