Inspired by the philosophy of nob.h, nob.hpp is a simple, self-contained, header-only library for building C++ projects using C++ itself.

Forget Makefiles, forget CMake. If you know C++, you already know how to use nob.hpp.

• No Dependencies: Besides a C++11 compliant compiler, you don't need anything else.
• Header-Only: Just drop nob.hpp into your project and you're ready to go.
• Use C++ to build C++: Write your build scripts in the same language as your project. No context switching, no learning new syntax.
• Self-Rebuilding: The build script can automatically rebuild itself if it or nob.hpp is updated.

Here is a simple example of a build script (nob.cpp) that compiles all .cpp files from a src directory into a single executable.

// nob.cpp
#include "nob.hpp"

int main(int argc, char* argv[])
{
    REBUILD_YOURSELF(argc, argv);

    const std::string build_dir = "./build";
    const std::string src_dir = "./src";

    if (!NOB::mkdir_if_not_exists(build_dir)) return 1;

    std::vector<NOB::Cmds> compile_cmds;
    std::vector<std::string> obj_paths;

    auto src_files = NOB::read_entire_dir(src_dir);
    for(const auto& file: src_files){
        if(NOB::is_src_file(file)){
            std::string src_path = src_dir + "/" + file;
            std::string obj_path = build_dir + "/" + file + ".o";
            obj_paths.push_back(obj_path);

            if (NOB::is_updated(src_path, obj_path)) {
                NOB::Cmds cmd;
                cmd.emplace_back("g++");
                cmd.emplace_back("-c");
                cmd.emplace_back("-o");
                cmd.emplace_back(obj_path);
                cmd.emplace_back(src_path);
                compile_cmds.push_back(cmd);
            }
        }
    }

    if (!compile_cmds.empty()) {
        NOB::INFO("Compiling...");
        if (!NOB::run_cmds_parallel(compile_cmds)) return 1;
    }

    NOB::INFO("Linking...");
    NOB::Cmds link_cmd;
    link_cmd.emplace_back("g++");
    link_cmd.emplace_back("-o");
    link_cmd.emplace_back(build_dir + "/main");
    for (const auto& path : obj_paths) {
        link_cmd.emplace_back(path);
    }

    if (!NOB::run_cmds(link_cmd)) return 1;

    NOB::INFO("Build finished successfully.");
    return 0;
}

How to run:

1. Bootstrap the build script:

   g++ -o nob nob.cpp

2. Run the build:

   ./nob

That's it! If you modify nob.cpp or nob.hpp, the nob executable will automatically rebuild itself on the next run.

All functions are available under the NOB namespace.

• void INFO(const std::string& msg): Prints an informational message.
• void WARN(const std::string& msg): Prints a warning message.
• void ERROR(const std::string& msg): Prints an error message.

• class Cmd: Represents a single part of a command.
• using Cmds = std::vector<Cmd>: Represents a full command line.
• bool run_cmds(const Cmds& cmds): Executes a command serially.
• bool run_cmds_parallel(const std::vector<Cmds>& cmd_groups): Executes multiple command groups in parallel (on POSIX systems).

• bool exists(const std::string& path): Checks if a file or directory exists.
• bool is_dir(const std::string& path): Checks if a path is a directory.
• bool mkdir_if_not_exists(const std::string& dir): Creates a directory if it does not exist.
• std::vector<std::string> read_entire_dir(const std::string& dir): Reads all entry names from a directory.
• std::vector<std::string> read_entire_dir_recursively(const std::string& dir): Reads all entry names from a directory recursively.
• bool remove_file(const std::string& path): Removes a file.
• bool remove_dir_recursively(const std::string& dir): Recursively removes a directory and its contents.

• bool is_src_file(const std::string& file): Returns true if the file has a .c, .cpp, or .cxx extension.
• bool is_header_file(const std::string& file): Returns true if the file has a .h, .hpp, or .hxx extension.
• bool is_updated(const std::string& src, const std::string& dst): Checks if the source file is newer than the destination file.

• REBUILD_YOURSELF(argc, argv): A macro that, when placed at the start of main, enables the build script to automatically update itself.