Explicit boolean option parsed into std::optional

[ottmar-zittlau]

Hi,

I would like to add a boolean option where the user explicitly needs to specify the value.
In addition, I want to parse this option into a std::optional, because later on it is relevant if the bool has been set or not.

I prepared a small example:

#include <CLI/CLI.hpp>
#include <iostream>
#include <optional>

int main(int argc, const char* argv[]){
    CLI::App app;
    
    bool flag = false;
    std::optional<bool> optional_flag = std::nullopt;

    app.add_option("--flag", flag, "description");
    app.add_option("--optional_flag", optional_flag, "description");
    
    app.parse(argc, argv);

    std::cout << "flag: " << flag << std::endl;
    
    if(optional_flag){
         std::cout << "optional flag: " << optional_flag.value() << std::endl;
    }
}

If I call this ./cli11_test --flag true --optional_flag true I get the error

terminate called after throwing an instance of 'CLI::ConversionError'
  what():  Could not convert: --optional_flag = true

I'm already using std::optional for options of type std::string and it works nicely. Can I also accomplish this here without explicitly checking the state of the underlying CLI::Option object?

Thanks and best regards
oz

[Philip Top]

I tried this and it works as expected with no errors. What compiler and CLI11 version are you using?

[ottmar-zittlau]

Thanks for the quick reply - I was using CLI11 v1.9.1 and gcc 12.
But now I tried with CLI11 v2.4.1 and it worked, thanks for the suggestion.