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gcontracts Status Update

I am currently working on the gcontracts 1.0.1 release [0]. Apart from bug fixes, that version contains an important feature you might have been tumbled over: class invariant checking on Groovy bean properties.

Groovy beans support a very simple syntax to declare properties [1]. E.g. adding a property firstName to your Person class is as simple as typing:

class Person {
    String firstName
    // ...    

Compared to its Java equivalent that is as simple as it can get.

public class Person {
    private String firstName;

    public void setFirstName(String anotherFirstName)  {
        firstName = anotherFirstName;

    public String getFirstName()  {
        return firstName;

Up to now, gcontracts injected class invariants only in explicitly declared setter methods, but users reported the need for class invariant injection on writeable POGO properties.

Today, i am glad to tell you that gcontracts class invariant injection mechanisms now works with POGO properties. Whenever a class declares an invariant, that invariant is injected in every dynamically generated setter method of that class.

E.g. a class invariant like,

@Invariant({ firstName != null })
class Person {
    String firstName
    // ...    

causes a java.lang.AssertionError whenever

def me = new Person("Andre")
me.firstName = null

is called.

Support for class invariant injection in POGO properties is currently available in github’s Master branch and will be part of gcontracts 1.0.1.

[0] Github – gcontracts
[1] Groovy Beans

Categories: gcontracts
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  1. April 27, 2010 at 6:54 am

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