Dynamic adaptation to the execution context is desirable in software that operates in an evolving environment. Context-oriented programming (COP) languages address behavioral variability from the programming-language perspective. COP has proven to be a valid approach when software is developed from scratch. However, it might require invasive, error-prone modifications when contextual variability is introduced to existing software written in non-COP languages, especially when variability is implicit in language constructs. A proposed approach moves variability support from the language to the language implementation level. This enables contextual variability in any application independently of whether the underlying language supports COP. A Neverlang-based prototype implementation illustrates this approach.