Re: getopt usage help to stderr?

[Salih Dincer via Digitalmars-d-learn]

On Tuesday, 8 April 2025 at 20:14:56 UTC, Andy Valencia wrote:

p.s. Ironically, I could probably have coded a getopt in less 
time than I've spent on std.getopt...

:)

Please try the following example with the parameters -h, -e, -l, 
and -v in that order:

```d
import std.array : appender;
import std.getopt, std.stdio;

void main(string[] args)
{
    enum errMsg = "\nPlease try again!";
    string test;
    bool verbose;

    try
    {
        auto rslt = getopt(
            args,
            "exit|e", "Exit process", &test,
            "verbose|v", "Enable verbose output", &verbose
        );

        if (rslt.helpWanted)
        {
            // Capture help text to a string
            import std.array : appender;
            import std.format : formattedWrite;

            auto helpText = appender!string();
            defaultGetoptFormatter(helpText, args[0], 
rslt.options);

            // Output to stderr
            stderr.write(helpText.data);
            return;
        }
    }
    catch (Exception e)
    {
        stderr.writeln(e.msg, errMsg); // ... Please try again!
        // Also output help on error
        auto helpText = appender!string();
        defaultGetoptFormatter(helpText, args[0], 
getopt(args).options);
        stderr.write(helpText.data);
        return;
    }

    // Your program logic here
    if (verbose)
      writeln("Verbose Mode: on");
}

```

SDB@79