When, if ever, is “number of lines of code” a useful metric?

Question

Some people claim that code\'s worst enemy is its size, and I tend to agree. Yet every day you keep hearing things like

• I write blah lines of code in a day.

Answer 1

I wrote 2 blog post detailling the pro and cons of counting Lines of Code (LoC):

How do you count your number of Lines Of Code (LOC) ? : The idea is to explain that you need to count the logical number of lines of code instead of a physical count. To do so you can use tools like NDepend for example.

Why is it useful to count the number of Lines Of Code (LOC) ?: The idea is that LoC should never be used to measure productivity, but more to do test coverage estimation and software deadline estimation.

Answer 2

It seems to me that there's a finite limit of how many lines of code I can refer to off the top of my head from any given project. The limit is probably very similar for the average programmer. Therefore, if you know your project has 2 million lines of code, and your programmers can be expected to be able to understand whether or not a bug is related to the 5K lines of code they know well, then you know you need to hire 400 programmers for your code base to be well covered from someone's memory.

This will also make you think twice about growing your code base too fast and might get you thinking about refactoring it to make it more understandable.

Note I made up these numbers.

Answer 3

When you have to budget for the number of punch cards you need to order.

Answer 4

Answer: when you can talk about negative lines of code. As in: "I removed 40 extraneous lines of code today, and the program is still functioning as well as before."

Answer 5

Check out wikipedia's definition: http://en.wikipedia.org/wiki/Source_lines_of_code

SLOC = 'source lines of code'

There is actually quite a bit of time put into these metrics where I work. There are also different ways to count SLOC.

From the wikipedia article:

There are two major types of SLOC measures: physical SLOC and logical SLOC.

Another good resource: http://www.dwheeler.com/sloc/

Answer 6

To paraphrase a quote I read about 25 years ago,

"The problem with using lines of code as a metric is it measures the complexity of the solution, not the complexity of the problem".

I believe the quote is from David Parnas in an article in the Journal of the ACM.