Validating an option using a different option's value

[dmf254]

Greetings all, love the library. I'd like to validate an option range that is dependent on another option. I think this code snippet will show what I intend.

MyApp::MyApp() : CLI::App("Description", "Appname")
{

client_cnt = 100;
clientidx_start = 0;

add_option("--client-cnt", client_cnt)->check(CLI::Range(1, 10000));
add_option("--clientidx-start", clientidx_start)->check(CLI::PositiveNumber & CLI::Validator([&]() {
        if ((client_cnt + clientidx_start) > 10000) {
            return "The number of clients exceeds the maxmium client index of 10000";
        }
        return "";
    }));
}

I'm essentially wanting to constrain these two options such that (client_cnt + clientidx_start) is < 10000. What would be the best way to do this? (The validator + lambda are more for show, not correct)

Thanks!

[phlptp]

MyApp::MyApp() : CLI::App("Description", "Appname")
{

client_cnt = 100;
clientidx_start = 0;

add_option("--client-cnt", client_cnt)->check(CLI::Range(1, 10000))->trigger_on_parse();
add_option("--clientidx-start", clientidx_start)->check(CLI::PositiveNumber & CLI::Validator([&](const std::string &checkString) {
        std::uint32_t val{0};
        details::lexical_cast(checkString, val);
        if ((client_cnt + val) > 10000) {
            return "The number of clients exceeds the maximum client index of 10000";
        }
        return "";
    }));
}

I think this will work(haven't checked exactly).
Two things, --client-cnt would have the trigger_on_parse() modifier set, this means this value will get set when parsed so before the other one. Then you just need to do the validation in the second option and handle the string conversion. You already do positive number so don't really need to check that again.

Another option would be just do the range checking individually and add a small callback on the app itself that will run after all the individual options, that does a final check and throws a CLI::ValidationError("error message") if the check doesn't pass.

That would look like

MyApp::MyApp() : CLI::App("Description", "Appname")
{

client_cnt = 100;
clientidx_start = 0;

add_option("--client-cnt", client_cnt)->check(CLI::Range(1, 10000));
add_option("--clientidx-start", clientidx_start)->check(CLI::Range(0, 9998));
final_callback([&]() {
        if ((client_cnt + clientidx_start) > 10000) {
            throw CLI::ValidationError("The number of clients exceeds the maximum client index of 10000");
        }
    });
}

[dmf254]

Thanks a bunch! I'm going to try both these out.