From the course: Advanced C++: Building Projects with CMake

Why use a build system? - C++ Tutorial

From the course: Advanced C++: Building Projects with CMake

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Why use a build system?

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- [Instructor] Before we dive into CMiC specifically, let's talk about build systems. At their core, build systems solve a fundamental problem. They automate the process of transforming your source code into executable programs. But they do much more than just run the compiler and linker. A good build system maintains consistency across environments, reduces redundant work, and improves the overall reliability of your development process. C++ projects are particularly challenging because of several factors. Header dependencies create complex dependency chains that aren't immediately obvious. Platform differences in compilers, libraries, and system cause demand different build approaches. Library linkage varies significantly across systems. Pre-processing directives can change what code actually gets compiled. And configuration options multiply the number of possible build combinations. Here's a simple example. Imagine we have a basic project with just three files. Both main.cpp and Utils.cpp include the header. Thus, when you modify Util.h, both main.cpp and Utils.cpp need recompilation. Now imagine this with hundreds of files and complex inclusion hierarchies. In what order should compilation happen? How should different compilation options be applied for different platforms? A build system tracks these dependencies so it knows exactly what needs rebuilding after changes. It also ensures correct build ordering, minimizes unnecessary compilation, and handles platform specific aspects. Conversely, the limitations of a build system directly impact development. Slow builds destroy productivity. Platform-specific systems reduce portability. And poor dependency tracking leads to inconsistent builds and mysterious bugs. Now let's dive into the history and evolution of build systems. The first build system called Make was created by Stuart Feldman at Bell Labs in 1976. The project was inspired by the frustration of one of his colleagues, Steve Johnson, the author of the yacc. Steve wasted the morning hunting for a bug that had been fixed, but the source file hadn't been compiled. Stuart shared his colleague's pain, having dealt with a similar issue earlier. That's when he came up with the idea of a dependency analyzer, which it then turned into the first version of Make, over the weekend. Make introduced the concept of declarative dependency specifications. To describe the build logic, you create a Make file, a simple text file, by defining targets, dependencies, and rules. Make simplified and improved the build process using dependency ordering, and out-of-date checking by comparing source file timestamps with target files. While Make was revolutionary, it showed its limitations as projects grew in complexity and cross-platform needs emerged. This led to a proliferation of build systems. Other tools attempted to address cross-platform issues, but introduced its own complexity. Visual Studio created proprietary project fires that worked beautifully in Windows, but nowhere else. Perforce Jam was an open-source alternative to Make, while Ninja focuses on running builds as fast as possible. Each build system tried to address different aspects of the problem, but often at the cost of portability, readability, or ease of use. Throughout this course, we'll see how CMiC addresses these challenges with the flexible, cross-platform approach, making it the favorite build system for modern C++ development. But first, let's examine why CMiC has gained such widespread adoption compared to alternatives.

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