Software Product Lines (SPL) aims to reuse code and other artifacts in order to reduce costs and gain agility. Feature Oriented Programming (FOP) is a technique to develop SPLs that aims to improve the modularity and flexibility of feature code. The basic idea of FOP is to decompose software into smaller pieces, called features, so they can be composed according to the needs of each customer. Groovy programming language has no tool or framework that supports the implementation of FOP-SPLs. Groovy is a programming language that has been growing in popularity in recent years. Given this scenario, this work proposes and evaluates G4FOP, a practical way to develop SPLs using Groovy. G4FOP extends the framework FeatureHouse that is a framework for software composition. Our results show that G4FOP covers the Groovy grammar and, by a demonstration of use, that it is applicable to develop SPLs. G4FOP is currently integrated to the official FeatureHouse repository.