Groovy中 使用Tap方法轻松创建对象

/**
 * Sample class with some properties
 * and a method.
 */
class Sample {
     
    String username, email
     
    List<String> labels = []
     
    void addLabel(value) {
        labels << value
    }
     
}
 
// Use tap method to create instance of
// Sample and set properties and invoke methods.
def sample =
        new Sample().tap {
            assert delegate.class.name == 'Sample'
             
            username = 'mrhaki'
            email = 'email@host.com'
            addLabel 'Groovy'
            addLabel 'Gradle'
             
            // We use tap, an alias for with(true),
            // so the delegate of the closure,
            // the Sample object, is returned.
        }
 
assert sample.labels == ['Groovy', 'Gradle']
assert sample.username == 'mrhaki'
assert sample.email == 'email@host.com'

/**
 * Sample class with some properties
 * and a method.
 */
class Sample {
     
    String username, email
     
    List<String> labels = []
     
    void addLabel(value) {
        labels << value
    }
     
}
 
// Use with method to create instance of
// Sample and set properties and invoke methods.
def sample1 =
        new Sample().with {
            assert delegate.class.name == 'Sample'
 
            username = 'mrhaki'
            email = 'email@host.com'
            addLabel 'Groovy'
            addLabel 'Gradle'  
        }
        
// With method returns the result
// from the closure. In the previous
// case the return result is null,
// because the last statement addLabel
// is used as return value. addLabel has
// return type void.
assert !sample1
 
 
// Use with method to create instance of
// Sample and set properties and invoke methods.
def sample2 =
        new Sample().with {
            assert delegate.class.name == 'Sample'
 
            username = 'mrhaki'
            email = 'email@host.com'
            addLabel 'Groovy'
            addLabel 'Gradle'
             
            // Explicitly return delegate of
            // closure, which is the Sample object.
            return delegate
        }
 
assert sample2.labels == ['Groovy', 'Gradle']
assert sample2.username == 'mrhaki'
assert sample2.email == 'email@host.com'
 
 
// Use with method to create instance of
// Sample and set properties and invoke methods.
def sample3 =
        new Sample().with(true) {
            assert delegate.class.name == 'Sample'
 
            username = 'mrhaki'
            email = 'email@host.com'
            addLabel 'Groovy'
            addLabel 'Gradle'
             
            // We use with(true), so the
            // delegate of the closure, the Sample
            // object, is returned.
        }
 
assert sample3.labels == ['Groovy', 'Gradle']
assert sample3.username == 'mrhaki'
assert sample3.email == 'email@host.com'

/**
 * Sample class with some properties
 * and a method.
 */
class Sample {
     
    String username, email
     
    List<String> labels = []
     
    void addLabel(value) {
        labels << value
    }
     
}
 
def sample =
        new Sample().tap {
            username = 'mrhaki'
            email = 'email@host.com'
            addLabel 'Groovy'
            addLabel 'Gradle'
        }
 
// The with method can be very useful to
// transform object to another type using
// values from the object.
def user = sample.with { "$username likes ${labels.join(', ')}." }
 
assert user == 'mrhaki likes Groovy, Gradle.'