parse_complete_callback() prevents values from a config from being assigned

[The0Dev]

Hello. I've run into a strange issue. When I use the parse_complete_callback() function, values for options specified in a config file are not assigned to their respective variables. In this case, the flag_sub variable is always set to false, despite the fact that the config_to_str() function shows that --flag-sub=true.

./app sub

config.toml:

[sub]
flag-sub=true

#include <CLI/CLI.hpp>

struct Options
{
    bool flag_sub = false;
};

void SetupSub(CLI::App& app)
{
    auto opt = std::make_shared<Options>();

    auto* sub = app.add_subcommand("sub", "A subcommand");

    sub->add_flag("--flag-sub,!--no-flag-sub", opt->flag_sub, "flag sub")->default_val(false);
    //flag_sub is false
    //comment out this to fix the issue
    sub->parse_complete_callback([opt]()
    {
        std::cout << "Running the parse complete callback for the sub; flag-sub: " << opt->flag_sub << std::endl;
    });
    //flag_sub is still false unless you remove parse_complete_callback
    sub->callback([opt]()
    {
        std::cout << "Running the callback for the sub; flag-sub: " << opt->flag_sub << std::endl;
    });
}


int main(int argc, char** argv)
{
    CLI::App app{"My app"};

    //Specify your path to the config
    app.set_config("--conf", "/home/user/config.toml", "Set a config for the app");

    argv = app.ensure_utf8(argv);

    app.fallthrough();

    app.require_subcommand(0, 1);

    SetupSub(app);

    try
    {
        app.parse(argc, argv);
        std::cout << app.config_to_str() << std::endl;
    }
    catch(const CLI::ParseError &e)
    {
        return app.exit(e);
    }

}

The following is mentioned in README:

If the main app or subcommand has a config file, no data from the config file will be reflected in parse_complete_callback

Is it the case? Is it also expected that in a regular callback() no data from a config is available? The reason for such behavior is not immediately clear.

[phlptp]

The difference is that parse complete is run as soon as parsing the command line is completed. For some subcommands this means it can be called multiple times if multiple duplicate subcommands. This occurs prior to any processing of config file.

The regular callback is completed after all processing is completed, in which case all processing of config files will have been completed.

[The0Dev]

Thank you for your response.

The difference is that parse complete is run as soon as parsing the command line is completed. For some subcommands this means it can be called multiple times if multiple duplicate subcommands. This occurs prior to any processing of config file.

This clarifies some things. This detail should probably be mentioned in the code documentation.

The regular callback is completed after all processing is completed, in which case all processing of config files will have been completed.

In the code example I provided, the value of flag_sub does not match the value that is used in the config file when regular callback is evoked.