cptb

Abstract

An experiment to create a simple C++ toolbelt command line tool that should help with creating and building CMake/C++ projects and managing different combinations of toolchains and CMake versions. The inspiration are the 'cargo' and 'rustup' tools from the Rust world.

Objectives

Goals

• a single, standalone executable without dependencies
• allow for quick and easy start of a C++ project
• minimal manual setup required

Non-Goals

• a complete equivalent of rust/cargo for C++
• provide dozens of options to support any possible CI/unittesting/coverage/... combination for setup and configuration right at creation time
• C++ package manager that might replace Conan/Hunter/vcpkg/...

Some decisions

• Rust was used as implementation language because it was very easy to build a standalone executable without external dependencies right out of the box and because a lot of very helpful libraries are easily available in Rust, such as clap, handlebars, rust-embed, ... Additionally I really just wanted to create something productive in Rust ;-)

Requirements and building

To build the cptb executable you just need a decent Rust compiler with which you run

cargo build

Usage

Once you have built the cptb executable, unfortunately at the moment you still need to setup some manual configuration with your toolchains. After that however, building your project should be really easy.

Manual configuration

One of the strengths of cptb is the simplified handling of different toolchains which should be particularly helpful on Windows. To support this simplified toolchain handling, cptb needs a few configuration files.

The configuration is stored in %HOME_DIRECTORY%/.cptb. This directory requires two JSON-files that contain the CMake and toolchain descriptions. The file kits.json can contain multiple toolchain descriptions as follows:

{
    "compilers": {
        "mingw-8-1": {
            "name": "MinGW-w64 8.1.0 SEH",
            "path": "c:/mingw64/x86_64-8.1.0-release-win32-seh-rt_v6-rev0/bin",
            "cmake_generator": "MinGW Makefiles"
        }
    },
    "cmake": {
        "cmake-3-17": {
            "name": "CMake 3.17",
            "path": "C:/Program Files (x86)/CMake/bin"
        }
    },
    "kits": {
        "cmake-3-17_mingw-8-1": {
            "name": "MinGW 8.1.0; CMake 3.17",
            "compiler": "mingw-8-1",
            "cmake": "cmake-3-17"
        }
    }
}

The kits.json file contains arbitrary key names that describe individual kits. One such kit is then refered to from the settings.json file as the default_kit, which is used by cptb for building. The "toolchain" key is a path to the compiler executable. The "cmake" key describes the CMake version to be used for building. The "path" sub-key again describes the path to the cmake executable. The "generator" key is an optional key for giving the value to the -G parameter of CMake.

{
    "default_kit": "cmake-3-17_mingw-8-1"
}

Creating a new project

Switch to a directory in which you want to create your new C++ project and run

cptb new my_project

This will create a new directory called my_project which contains a simple hello world application written in C++ which could be built with CMake and a C++ compiler.

Building a project

When you have setup your toolchains properly as described above and have created a project, you can now build it. Simply change into the directory of the new project and run cptb build:

cd my_project
cptb build

The initial hello world project should build right out of the box and you should now have your executable inside the build/ folder of your project.

Getting a shell in the build environment

When running cptb build this will temporarily update the PATH variable and potentially other environment variables to perform the build itself. However after running the build subcommand, these changes are no longer visible.

To start a new shell with all environment variables set according to the build environment, simply run

cptb buildenv

Now you can run cmake, make or any other build tools available from your toolchain. In the new shell started by cptb you will see your original prompt prepended with a (cptb build) to indicate that you are in a special environment.

Leaving the build environment is as easy as

exit

License

MIT