C++ Idioms by Example

I read a lot of code. Often I like what I see, but sometimes I see code that is perfectly OK according to the definition of the language but which is flawed because it breaks too many established idioms and conventions of the language. There are plenty of really good books about this topic, but most of them start at a slightly too advanced level – they assume that the reader already know about the basic stuff.

I have tried to make a little contribution by illustrating some of the really basic C++ idioms and conventions using a contrived but still complete example. Please take a look at this presentation.

When presenting this stuff, I usually hand out the first code snippet to a group of people, then I do online coding while the group suggests improvements and we discuss why it is so. Interesting enough, it seems like we always end up roughly at the same place. This presentation is just one of several paths that might happen when a group decides what to improve or not.

Code Entropy

While preparing my talk at Smidig 2008 I kept thinking about the second law of thermodynamics.

Given two snippets of code, A and B, that have exactly the same external behaviour. If an expert programmer is more likely to change A to B than B to A, then snippet A has higher code entropy than snippet B.

Let us consider a very simple example:

{ int a=3; while (a<9) { ... ; a++; } } // snippet A

and

{ for (int a=3; a<9; a++) { ... } } // snippet B

The external behaviour for these two code snippets are exactly the same. However, most programmers would agree that snippet A is better rewritten into snippet B. So, in this example, during a refactoring session, it is likely that someone will change A into B, but unlikely that someone will change B into A. Hence snippet A has higher code entropy than snippet B.

Now, extend this idea into larger functions, classes, modules, applications, software design and architecture. Can entropy be used to describe the state of a codebase?