Function magnus::scan_args::check_arity

pub fn check_arity<T>(len: usize, bounds: T) -> Result<(), Error>where
    T: RangeBounds<usize>,

Returns Err containing a Ruby ArgumentError if len is not within bounds.

Examples

use magnus::{define_global_function, eval, function, scan_args::check_arity, Error, RArray, RString, Value};

fn example(args: &[Value]) -> Result<RString, Error> {
    check_arity(args.len(), 2..5)?;
    RArray::from_slice(args).join(", ")
}

define_global_function("example", function!(example, -1));

assert_eq!(eval::<String>("example(1)").unwrap_err().to_string(), "wrong number of arguments (given 1, expected 2..4)");
assert_eq!(eval::<String>("example(1, 2, 3, 4, 5)").unwrap_err().to_string(), "wrong number of arguments (given 5, expected 2..4)");