askalexsharov / imgdiff-cpp

ModernCppStarter

Setting up a new C++ project usually requires a significant amount of preparation and boilerplate code, even more so for modern C++ projects with tests, executables and continuous integration. This template is the result of learnings from many previous projects and should help reduce the work required to setup up a modern C++ project.

Features

• Modern CMake practices
• Suited for single header libraries and projects of any scale
• Clean separation of library and executable code
• Integrated test suite
• Continuous integration via GitHub Actions
• Code coverage via codecov
• Code formatting enforced by clang-format via Format.cmake
• Reproducible dependency management via CPM.cmake
• Installable target with automatic versioning information and header generation via PackageProject.cmake
• Automatic documentation and deployment with Doxygen and GitHub Pages
• Support for sanitizer tools, and more

Usage

Adjust the template to your needs

• Use this repo as a template and replace all occurrences of "Imgdiff" in the relevant CMakeLists.txt with the name of your project
• Replace the source files with your own
• For header-only libraries: see the comments in CMakeLists.txt
• Add your project's codecov token to your project's github secrets under CODECOV_TOKEN
• Happy coding!

Eventually, you can remove any unused files, such as the standalone directory or irrelevant github workflows for your project. Feel free to replace the License with one suited for your project.

Build and run the standalone target

Use the following command to build and run the executable target.

cmake -Hstandalone -Bbuild/standalone
cmake --build build/standalone
./build/standalone/Imgdiff --help

Build and run test suite

Use the following commands from the project's root directory to run the test suite.

cmake -Htest -Bbuild/test
cmake --build build/test
CTEST_OUTPUT_ON_FAILURE=1 cmake --build build/test --target test

# or simply call the executable: 
./build/test/GreeterTests

To collect code coverage information, run CMake with the -DENABLE_TEST_COVERAGE=1 option.

Run clang-format

Use the following commands from the project's root directory to run clang-format (must be installed on the host system).

cmake -Htest -Bbuild/test

# view changes
cmake --build build/test --target format

# apply changes
cmake --build build/test --target fix-format

See Format.cmake for more options.

Build the documentation

The documentation is automatically built and published whenever a GitHub Release is created. To manually build documentation, call the following command.

cmake -Hdocumentation -Bbuild/doc
cmake --build build/doc --target GenerateDocs
# view the docs
open build/doc/doxygen/html/index.html

Additional tools

The test and standalone subprojects include the tools.cmake file which is used to import additional tools on-demand through CMake configuration arguments. The following are currently supported.

Sanitizers

Sanitizers can be enabled by configuring CMake with -DUSE_SANITIZER=<Address | Memory | MemoryWithOrigins | Undefined | Thread | Leak | 'Address;Undefined'>.

Static Analyzers

Static Analyzers can be enabled by setting -DUSE_STATIC_ANALYZER=<clang-tidy | iwyu | cppcheck>, or a combination of those in quotation marks, separated by semicolons. By default, analyzers will automatically find configuration files such as .clang-format. Additional arguments can be passed to the analyzers by setting the CLANG_TIDY_ARGS, IWYU_ARGS or CPPCHECK_ARGS variables.

Ccache

Ccache can be enabled by configuring with -DUSE_CCACHE=<ON | OFF>.

FAQ

Can I use this for header-only libraries?

Yes, however you will need to change the library type to an INTERFACE library as documented in the CMakeLists.txt. See here for an example header-only library based on the template.

I don't need a standalone target / documentation. How can I get rid of it?

Simply remove the standalone / documentation directory and according github workflow file.

Can I build the standalone and tests at the same time?

To keep the template modular, projects have been separated into their own CMake modules. However it's easy to create a new directory, say all, that uses CPMAddProject to add both the standalone and the tests as well as any other subprojects to a single build. Note, that it's not recommended to include the standalone or tests from the main CMakeLists, as it will make the project more difficult for others to use as a library.

I see you are using GLOB to add source files in CMakeLists.txt. Isn't that evil?

Glob is considered bad because any changes to the source file structure might not be automatically caught by CMake's builders and you will need to manually invoke CMake on changes. I personally prefer the GLOB solution for its simplicity, but feel free to change it to explicitly listing sources.

I want create additional targets that depend on my library. Should I modify the main CMakeLists to include them?

Avoid including derived projects from the libraries CMakeLists (even though it is a common sight in the C++ world), as this effectively inverts the dependency tree and makes the build system hard to reason about. Instead, create a new directory or project with a CMakeLists that adds the library as a dependency (e.g. like the standalone directory). Depending type it might make sense move these components into a separate repositories and reference a specific commit or version of the library. This has the advantage that individual libraries and components can be improved and updated independently.

You recommend to add external dependencies using CPM.cmake. Will this force users of my library to use CPM as well?

CPM.cmake should be invisible to library users as it's a self-contained CMake Script. If problems do arise, users can always opt-out by defining CPM_USE_LOCAL_PACKAGES, which will override all calls to CPMAddPackage with find_package. Alternatively, you could use CPMFindPackage instead of CPMAddPackage, which will try to use find_package before calling CPMAddPackage as a fallback. Both approaches should be compatible with common C++ package managers without modifications, however come with the cost of reproducible builds.

Can I configure and build my project offline?

Using CPM, all missing dependencies are downloaded at configure time. To avoid redundant downloads, it's recommended to set a CPM cache directory, e.g.: export CPM_SOURCE_CACHE=$HOME/.cache/CPM. This will also allow offline configurations if all dependencies are present. No internet connection is required for building.

Can I use CPack to create a package installer for my project?

As there are a lot of possible options and configurations, this is not (yet) in the scope of this template. See the CPack documentation for more information on setting up CPack installers.

This is too much, I just want to play with C++ code and test some libraries.

Perhaps the MiniCppStarter is something for you!

Coming soon

• Script to automatically adjust the template for new projects