v/examples/compiletime/reflection.v

// An example deserializer implementation

struct User {
	name string
	age  int
}

fn main() {
	data := 'name=Alice\nage=18'
	user := decode<User>(data)
	println(user)
}

fn decode<T>(data string) T {
	mut result := T{}
	// compile-time `for` loop
	// T.fields gives an array of a field metadata type
	$for field in T.fields {
		$if field.typ is string {
			// $(string_expr) produces an identifier
			result.$(field.name) = get_string(data, field.name)
		} $else $if field.typ is int {
			result.$(field.name) = get_int(data, field.name)
		}
	}
	return result
}

fn get_string(data string, field_name string) string {
	for line in data.split_into_lines() {
		key_val := line.split('=')
		if key_val[0] == field_name {
			return key_val[1]
		}
	}
	return ''
}

fn get_int(data string, field string) int {
	return get_string(data, field).int()
}

// `decode<User>` generates:
// fn decode_User(data string) User {
//     mut result := User{}
//     result.name = get_string(data, 'name')
//     result.age = get_int(data, 'age')
//     return result
// }