Exceptional C++: 47 Engineering Puzzles, Programming Problems, and Solutions

Chapter 26. Minimizing Compile-time Dependencies—Part 1

Difficulty: 4

When we talk about dependencies, we usually think of run-time dependencies like class interactions. In this Item, we will focus instead on how to analyze and manage compile-time dependencies. As a first step, try to identify (and root out) unnecessary headers.

Many programmers habitually #include many more headers than necessary. Unfortunately, doing so can seriously degrade build times, especially when a popular header file includes too many other headers.

In the following header file, which #include directives could be immediately removed without ill effect? You may not make any changes other than removing or rewriting #include directives. Note that the comments are important. ...