Groovy Goodness: Override getProperty Method with Dynamic Groovy

Groovy's ExpandoMetaClass features allows us to override the getProperty() method for a class. This method is invoked if we want to access a property for an object. We can look up existing properties and return their result, but we can also write behaviour for the situation when the property doesn't exist.

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class User {     String username }   User.metaClass.getProperty = { String propName ->     def meta = User.metaClass.getMetaProperty(propName)     if (meta) {         meta.getProperty(delegate)     } else {         'Dynamic property for User'     } }   def mrhaki = new User(username: 'mrhaki') def hubert = new User(username: 'hubert')   assert 'mrhaki' == mrhaki.username assert 'Dynamic property for User' == mrhaki.fullname