What is CMake?
According to CMake’s creators, Kitware, CMake is an open-source cross
platform build system. This is not completely accurate as CMake is not
actually a build system. What CMake provides is an easy way to build C/C++
projects across platforms. The reason I say that CMake isn’t a build system
is because it doesn’t actually build software. “A build system
that doesn’t build software?” you ask. Yes; what CMake does is
generate a configuration for your existing build system, e.g. Make. This
allows CMake to focus on things that most build systems don’t; such as cross
platform configuration, dependency calculation, testing, packaging, and
By not being a true build system, per se, CMake allows for a more flexible
development environment as it can generate Makefiles or projects for a
variety of IDEs. This allows developers to easily work on different
platforms using different tools since one can build using Microsoft’s Visual
Studio on Windows or with GNU Make on Linux just as easily.
CMake also includes tools for finding libraries, e.g. boost, and the ability
to easily include external projects in your build. These two features, in
particular, make it much simpler to build projects that have external
dependencies and by using the find tools rather than hard coding paths it is
much easier for new developers to get started on an existing project.
Included with CMake is CTest, a test driver program. Both work together to
make it easy to run a project’s test programs and/or scripts. When you
configure your project you specify how to run your tests and CMake generates
a configuration for CTest. CTest will run all of your tests and provide a
summary of which ones passed and which ones failed. In addition it logs the
output of all the tests it ran. Optionally CTest can be directed to run only
specific tests or skip specific tests, perhaps the slow ones. While it may
not be a continuous build system you have most of the components provided.
In addition to setting up a build CMake can also create an install target
that will install the outputs of your project in the appropriate
locations. Once you have configured your project to be installed you can
also package your project using the included CPack utility. A variety of
packages can be created including tar files, zip files, or an installer.
I would like to thank the following people for their help and contributions
to this tutorial. Without them it would not exist.
- Devin Ronge
This tutorial would not exist without Devin, he suggested I write it and
developer Devin has read every word of this tutorial at least once. Thanks
to him you get a better written tutorial than you would had he not
proof-read it first.
- Steve Rieman
As a C++ developer who actively uses CMake Steve has provided a technical
review of the sample code in addition to a review of the prose. He has
also provided numerous ideas for the contents of this tutorial.
The entire tutorial can be downloaded as a PDF file.