RESOURCE: Writing an extension to add new GREL functions to OpenRefine

Owen Stephens (Open University) has authored a post documenting the development of the Google Refine Expression Language (GREL) extension he wrote to add functionality to OpenRefine.

[W]hile OpenRefine extensions could be complex, writing one that simply added a new GREL function was quite straightforward with a little boilerplate code and the actual GREL function written in Java – and even with very little (pretty much zero) experience of writing Java I could manage to write a new function and bundle it in an extension with very little effort – this is my attempt to document that process – any corrections or additions to what I’ve written here are very welcome via the comments.

Stephens cites multiple documentation sites and users that will be helpful to practitioners consider their extensions and use of OpenRefine.