Making Software

The Systems

Software development projects vary in many dimensions: the domain of the project, the expertise of the developers, the size of the project, and the programming languages used to express the source code comprising the system, to name just a few. We want the projects we analyze for the purpose of investigating the questions of interest to vary across at least some of these dimensions. We also want projects that have archival information about the software development available. Many projects meet these criteria. We chose to include in our analyses the following three projects:

• Evolution (http://projects.gnome.org/evolution), an integrated email, address book, and calendar application included in the GNOME desktop (http://gnome.org)

• Mozilla Firefox (http://www.mozilla.com/firefox), a popular cross-platform web browser

• Mylyn (http://www.eclipse.org/mylyn), a task-focused interface for Eclipse (http://www.eclipse.org) that is included in the standard Eclipse distribution

Table 21-1 demonstrates the variability in these projects by providing an overview of these projects in terms of the length of the development, the primary language used to express the source code, the number of modules (see What Is a Module?), lines of code, and changes (see What Is a Change?). Only changes that were analyzed in our study are included in these counts.

Table 21-1. An overview of the three systems we analyzed

Project	First release	Primary language	Modules	Approximate SLOC[a]	Changes
Evolution ...