cor-args

A Rust library providing Chain of Responsibility command line argument parsing.

Examples

Example 1

The following example will assign config_path according to the following sequence:

1. Look for a command-line argument named --config
2. Look for an environment variable named MYAPP_config
3. Default to ~/.config/myapp/default.yaml

// Don't forget to add `clap` to your `Cargo.toml`
let args = clap::Command::new("myapp")
    .arg(clap::Arg::new("config").long("config"))
    .get_matches();

let config_path = ArgHandler::new(&args)
    .next(
        EnvHandler::new()
        .prefix("MYAPP_")
        .next(
            DefaultHandler::new("~/.config/myapp/default.yaml").into()
        ).into()
    );
    .handle_request("config");
let config_path = config_path.expect("No config path");

Example 2

The following example will assign some_value according to the following sequence:

1. Look for a command-line argument named --some_key
2. Look for an environment variable named MYAPP_some_key
3. The contents of the file /path/to/file.txt
4. Look for a key within file.json named some_key
5. Default to "some_value"

// Don't forget to add `clap` to your `Cargo.toml`
let args = clap::Command::new("myapp")
    .arg(clap::Arg::new("some_key").long("some_key"))
    .get_matches();

let handler = ArgHandler::new(&args)
    .next(EnvHandler::new()
        .next(FileHandler::new("/path/to/file.txt")
            .next(JSONFileHandler::new("file.json")
                .next(DefaultHandler::new("some_value").into())
            .into())
        .into())
    .into());
let some_value = handler.handle_request("some_key");