Making a git clone

Let's try our hand at a little git clone, called geet. It will just print it's intent, rather than running actual code, since it's just a demonstration. Let's start by adding an app and requiring 1 subcommand to run:

CLI::App app{"Geet, a command line git lookalike that does nothing"};
app.require_subcommand(1);

Now, let's define the first subcommand, add, along with a few options:

auto add = app.add_subcommand("add", "Add file(s)");

bool add_update;
add->add_flag("-u,--update", add_update, "Add updated files only");

std::vector<std::string> add_files;
add->add_option("files", add_files, "Files to add");

add->callback([&]() {
    std::cout << "Adding:";
    if(add_files.empty()) {
        if(add_update)
            std::cout << " all updated files";
        else
            std::cout << " all files";
    } else {
        for(auto file : add_files)
            std::cout << " " << file;
    }
});

Now, let's add commit:

auto commit = app.add_subcommand("commit", "Commit files");

std::string commit_message;
commit->add_option("-m,--message", commit_message, "A message")->required();

commit->callback([&]() { std::cout << "Commit message: " << commit_message; });

All that's need now is the parse call. We'll print a little message after the code runs, and then return:

CLI11_PARSE(app, argc, argv);

std::cout << "\nThanks for using geet!\n" << std::endl;
return 0;

Source code

If you compile and run:

gitbook:examples $ c++ -std=c++11 geet.cpp -o geet

You'll see it behaves pretty much like git.

Multi-file App parse code

This example could be made much nicer if it was split into files, one per subcommand. If you simply use shared pointers instead of raw values in the lambda capture, you can tie the lifetime to the lambda function lifetime. CLI11 has a multifile example in its example folder.