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# 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 contiguous 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
- Separation into library and executable code
- Integrated test suite
- Continuous integration via [GitHub Actions](https://help.github.com/en/actions/)
- Code coverage via [codecov](https://codecov.io)
- Code formatting enforced by [clang-format](https://clang.llvm.org/docs/ClangFormat.html) via [Format.cmake](https://github.com/TheLartians/Format.cmake)
- Reproducible dependency management via [CPM.cmake](https://github.com/TheLartians/CPM.cmake)
- Installable target with versioning information via [PackageProject.cmake](https://github.com/TheLartians/PackageProject.cmake)
- Support for [sanitizer tools and more](#additional-tools)

## Usage

### Adjust the template to your needs

- Use this repo [as a template](https://help.github.com/en/github/creating-cloning-and-archiving-repositories/creating-a-repository-from-a-template) and replace all occurrences of "Greeter" in the relevant CMakeLists.txt with the name of your project
- Replace the source files with your own
- For single-header libraries: see the comments in [CMakeLists.txt](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.

```bash
cmake -Hstandalone -Bbuild/standalone
cmake --build build/standalone
./build/standalone/Greeter --help
```

### Build and run test suite

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

```bash
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).

```bash
cmake -Htest -Bbuild/test

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

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

See [Format.cmake](https://github.com/TheLartians/Format.cmake) for more options.

### Additional tools

The project includes an [tools.cmake](cmake/tools.cmake) file that can be used to import additional tools on-demand through CMake configuration arguments.
The following are currently supported.

- `-DUSE_SANITIZER=<Address | Memory | MemoryWithOrigins | Undefined | Thread | Leak | 'Address;Undefined'>`
- `-DUSE_CCACHE=<YES | NO>`

## 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](CMakeLists.txt).

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

Simply remove the standalone directory and github workflow file.

> 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](https://cmake.org/cmake/help/latest/command/file.html#filesystem) 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 to add additional targets to my project. Should I modify the main CMakeLists to conditionally include them?

If possible, avoid adding conditional includes to the CMakeLists (even though it is a common sight in the C++ world), as it makes the build system convoluted and hard to reason about.
Instead, create a new directory with a CMakeLists that adds the main project as a dependency (e.g. just copy the [standalone](standalone) directory).
Depending on the complexity of the project it might make sense move the components into separate repositories and use CPM.cmake to add them as dependencies.
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](https://github.com/TheLartians/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](https://cmake.org/cmake/help/latest/module/CPack.html) for more information on setting up CPack installers.

## Coming soon

- Script to automatically adjust the template for new projects