Credits

• Many of the following slides are adapted from the slides for the book "Software Engineering: The Current Practice" by Vaclav Rajlich © 2012 by Václav Rajlich

Software Change

Software Change (SC) is the process of changing existing code

• Foundation of
• Software Evolution
• Agile processes
• Types
• New functionality changes
• Maintenance changes

Maintenance Change Categories [Lietz, et al. '78]

• perfective - improve documentation, rewrite code for computational efficiency, improve software design
• adaptive - accommodate changes to data inputs, files, and hardware and system software
• corrective - emergency fixes, routine debugging
• other

Maintenance Change Distribution

Maintenance Change Distribution

Concept Location

• Concepts extracted from the change request
• Extracted concepts are located in the code and used as a starting point for software change

Concept Location Examples

• Add Discover card for possible credit cards → Classes, methods, and data structures that involve other credit cards
• Fix the spelling of "password" (from "passwd") → find out where "passwd" is in the system
• Change API method length() to size() → Rename method refactoring in API

Impact Analysis

Determine the impact of change on an existing system

• Change has not occurred yet
• Typically done at a class/file level
• impact set classes identified in concept location
• Class dependencies are analyzed, and impacted classes are added to the impact set

In Practice

• Software changes need to be identified, classified, planned, and executed
• Concept location determines where a change needs to occur in the code. Can use regular expressions (i.e., regex) or the structure of the code.
• Impact analysis used to determine the change's effect on the entire system.
• The decision might be to not perform the software change.