Origins of poor code readability

The topic of source code readability has paramount importance in software engineering. Literature exists on how to write readable code; how to create analytical models and automatically predict readability; and how readability influences software cost and eventually the economy. In this article we follow a different path; we explore the question of why and how unreadable code gets written. Motivation The software community is increasingly concerned about the code readability (Buse et al. 2010): The readability of source code is related to its maintainability, and is thus a key factor in overall software quality. Typically, maintenance consumes over 70% of the total lifecycle cost of a software product (Boehm 2001). Aggarwal claims that source code readability and documentation readability are both critical to the maintainability of a project. Other researchers have noted that the act of reading code is the most time-consuming component of all maintenance activities. Readability is so significant, in fact, that Elshoff and Marcotty, after recognizing that many commercial programs were much more difficult to read than necessary, proposed adding a development phase in which the program is made more readable. Knight and Myers suggested that one phase of software inspection should be a check of the source code for readability to ensure maintainability, portability, and reusability of the code. Readability is a human judgment of how easy it is to understand program source code. It is important to note that readability is unrelated to functionality; the readability of source code can be increased or decreased without affecting program correctness. Unlike some other aspects which have objective definitions readability is always subjective. As the proverb goes, “Beauty is in the eye of the beholder;” readability is very much a human construct. What constitutes readable code may differ from programmer to programmer or from one group of programmers to another, or from programmers of one language to programmers of another language. We recognize this subjectivity on small snippets of code, but we believe that for relatively significant chunks of code (for example, a class definition and implementation), the human judgment generally reaches agreement. In this article, we first explore the various importance of readability. Later, we explore how and why readability gets compromised. 1 The opinions expressed in this article are solely the author’s – not his employer’s.