Groovy 中的 with

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// PrintIndependenceDay.java

import java.util.Calendar;
import java.util.Date;

public class PrintIndependenceDay {

  public static void main(String[] args) {
    Calendar calendar = Calendar.getInstance();
    calendar.clear();
    calendar.set(Calendar.MONTH, Calendar.JULY);
    calendar.set(Calendar.DATE, 4);
    calendar.set(Calendar.YEAR, 1776);
    Date time = calendar.getTime();
    System.out.println(time);
  }
}

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// PrintIndependenceDay.groovy

def calendar = Calendar.instance
calendar.with {
  clear()
  set MONTH, JULY
  set DATE, 4
  set YEAR, 1776
  println time
}

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// define a closure
def myClosure = {
  // call a method that does not exist
  append 'Jeff'
  append ' was here.'
}

// assign a delegate to the closure
def sb = new StringBuffer()
myClosure.delegate = sb

// execute the closure
myClosure()

assert 'Jeff was here.' == sb.toString()

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def closure = {
  clear()
  set MONTH, JULY
  set DATE, 4
  set YEAR, 1776
  println time
}
def calendar = Calendar.instance
closure.delegate = calendar
closure()

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class ResolutionTest {
    
    def append(arg) {
        println "you called the append method and passed ${arg}"
    }
    
    def doIt() {
        def closure = {
            append 'Jeff was here.'
        }
        
        def buffer = new StringBuffer()
        
        closure.delegate = buffer
        
        // the append method in this ResolutionTest
        // will be called because resolveStrategy is
        // OWNER_FIRST (the default)
        closure()
        
        // give the delegate first crack at method
        // calls made inside the closure
        closure.resolveStrategy = Closure.DELEGATE_FIRST
        
        // the append method on buffer will
        // be called because the delegate gets
        // first crack at the call to append()
        closure()
    }
    
    static void main(String[] a) {
        new ResolutionTest().doIt()
    }
}

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you called the append method and passed Jeff was here.