Optionalarg provides a convenient way to pass optional arguments. It is a light-weight way to define options.

The idea is define a distinct type for each parameter, and use type reflection to match parameters with arguments.

For example, to pass two optional string options to a function Foo, define two types for the options,

type Name string
type Value string

and pass the options to Foo,

Foo(Value("world"), Name("world"))

Foo uses optionalarg.Set to set the arguments,

func Foo(args ...interface{}) {
	var name, value string
	optionalarg.Set(args, (*Name)(&name), (*Value)(&value))
	...
}