Scheme

Run

C++

C++11

Program Comprehension

How software engineers understand and make changes to existing source code

• AKA program understanding

Program Comprehension Type

• Language
• API/library
• Platform
• Domain
• Programming Style

Language Comprehension

• Understanding of the basic syntax
• Ability to read programs in a language
• e.g., read and understand what a for loop is doing
• Ability to write programs in a language
• e.g., implement and write a for loop
• Know the language paradigm, e.g., object-oriented languages
• Know the general family of languages, e.g., know C++ but can follow Java

API/Library Comprehension

• Know the APIs and programming libraries used
• E.g., std::vector, std::copy(), std::iostream, std::ostream_iterator
• Based on identifiers and text in comments
• Impossible to know all parts of a modern API/library
• If APIs or libraries are consistent, then you can apply knowledge of good examples to the entire API/library

Platform

• Have to be able to build and run
• E.g., C++: g++ to build, run the executable directly
• Knowledge of IDE, build tools, and version control
• IDEs make things easier but introduce additional complications

Platform Complexity

• Non-native apps
• iOS apps
• Simulator
• Android apps
• Emulator
• Cloud applications
• Move from x86 to ARM, e.g., Fugaku, ARM cheaper per core
• So what do you use on your desktop?

Domain

• Based on identifiers and text in comments
• E.g., Gamma
• E.g., Stencil Library
• E.g., Networking
• These solutions apply to specific domains and are only understandable to someone who is solving problems in that domain

Domain Example 1

Domain Example 2

Domain Example 3

Programming Style

• E.g., Obfuscated C
• Inconsistency of programming style impedes comprehension
• Bad programming style interferes with search