OTUS C++ Course

OTUS Course C++ for professionals. The project layout based on Jason Turner cpp_starter_project.

Necessary Dependencies

1. A C++ compiler that supports C++17. See cppreference.com to see which features are supported by each compiler. The following compilers should work:

   • gcc 7+

     Install command

     • Debian/Ubuntu:

       sudo apt install build-essential

     • MacOS:

       brew install gcc

   • clang 6+

     Install command

     • Debian/Ubuntu:

       bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)"

     • MacOS:

       brew install llvm

2. Conan

   Install Command

   • Via pip - https://docs.conan.io/en/latest/installation.html#install-with-pip-recommended

     pip install --user conan

   • MacOS:

     brew install conan

3. CMake 3.15+

   Install Command

   • Debian/Ubuntu:

     sudo apt-get install cmake

   • MacOS:

     brew install cmake

Build Instructions

Build directory

All homework projects have a protection to prevent build from source code directory. So first of all nake a build directory:

mkdir build

Specify the compiler using environment variables

By default (if you don't set environment variables CC and CXX), the system default compiler will be used.

Conan and CMake use the environment variables CC and CXX to decide which compiler to use. So to avoid the conflict issues only specify the compilers using these variables.

CMake will detect which compiler was used to build each of the Conan targets. If you build all of your Conan targets with one compiler, and then build your CMake targets with a different compiler, the project may fail to build.

Commands for setting the compilers

• Debian/Ubuntu/MacOS:

  Set your desired compiler (clang, gcc, etc):

  • Temporarily (only for the current shell)

    Run one of the followings in the terminal:

    • clang

      CC=clang CXX=clang++
      

    • gcc

      CC=gcc CXX=g++
      

  • Permanent:

    Open ~/.bashrc using your text editor:

    gedit ~/.bashrc

    Add CC and CXX to point to the compilers:

    export CC=clang export CXX=clang++

    Save and close the file.

• Temporarily (only for the current shell):

    $Env:CC="clang.exe"
    $Env:CXX="clang++.exe"
  

Build

Once you have selected all the options you would like to use, you can build the project (all targets):

cmake --build ./build

Troubleshooting

Cmake build generation doesn't work

If you see the following error message:

CMake Error at cmake/PreventInSourceBuilds.cmake:14 (message):
Quitting configuration

That means you are trying to build in the source directory. Just follow the Build Instructions above.

Update Conan

Many problems that users have can be resolved by updating Conan, so if you are having any trouble with this project, you should start by doing that.

To update conan:

$ pip install --user --upgrade conan 

You may need to use pip3 instead of pip in this command, depending on your platform.

Clear Conan cache

If you continue to have trouble with your Conan dependencies, you can try clearing your Conan cache:

$ conan remove -f '*'

The next time you run cmake or cmake --build, your Conan dependencies will be rebuilt. If you aren't using your system's default compiler, don't forget to set the CC, CXX, CMAKE_C_COMPILER, and CMAKE_CXX_COMPILER variables, as described in the 'Build using an alternate compiler' section above.

Identifying misconfiguration of Conan dependencies

If you have a dependency 'A' that requires a specific version of another dependency 'B', and your project is trying to use the wrong version of dependency 'B', Conan will produce warnings about this configuration error when you run CMake. These warnings can easily get lost between a couple hundred or thousand lines of output, depending on the size of your project.

If your project has a Conan configuration error, you can use conan info to find it. conan info displays information about the dependency graph of your project, with colorized output in some terminals.

$ cd build
$ conan info .

In my terminal, the first couple lines of conan info's output show all of the project's configuration warnings in a bright yellow font.

For example, the package spdlog/1.5.0 depends on the package fmt/6.1.2. If you were to modify the file cmake/Conan.cmake so that it requires an earlier version of fmt, such as fmt/6.0.0, and then run:

$ conan remove -f '*'       # clear Conan cache
$ rm -rf build              # clear previous CMake build
$ mkdir build && cd build
$ cmake ..                  # rebuild Conan dependencies
$ conan info .

...the first line of output would be a warning that spdlog needs a more recent version of fmt.

Testing

See Catch2 tutorial

Homeworks

See another README.MD