Chant

Nonterminals smell that were “defined” in natural language instead of the actual grammar notation: “defined similarly to...”, “all Unicode characters of class...”, “any of the following”, etc. These are drastic examples of this smell, since they make the grammar completely useless for automatic machine consumption, and require a human expert to either fix the grammar or devise a semiparsing workaround, and possibly an extra person to translate the description to a natural language understandable by the expert.

Related smells: Debt

Reference

Mats Stijlaart and Vadim Zaytsev. 2017. Towards a taxonomy of grammar smells. In Proceedings of the 10th ACM SIGPLAN International Conference on Software Language Engineering (SLE 2017). ACM, New York, NY, USA, 43-54.