sample of use

sampleUse.groovy

class Hoge {
    static String hoge(String delegate) {
        return "HOGE: $delegate"
    }
    static String foo(String delegate, String param) {
        return "FOO: $delegate ($param)"
    }
    static String bar(Class<String> string) {
        return "BAR"
    }
    static String baz(Class<String> string) {
        if (!string?.isAssignableFrom(String)) {
            throw new ClassCastException("String only")
        }
        return "BAZ"
    }
}

use(Hoge) {
    println "A"
    println "A".hoge()
    println "A".foo()
    println "A".foo("BAR")
    println String.bar()
    println Integer.bar() // 誤爆
    println String.baz()
    println Integer.baz() // ClassCastException: String only
}