Spellchecking for Programmers

Sometimes Mac OS X’s workstation legacy shines through. In TextEdit (Mail, and other Cocoa Text applications), I enable Edit > Spelling and Grammar > Check Spelling While Typing. Sometimes I write identifiers InCamelCase. Today, I noticed that Cocoa correctly checks spelling of camelCase identifiers by splitting the identifier at case change boundaries, checking each component as a word, and marking the whole identifier as misspelled if any of the component words are. (camelCase is fine, but camlCase gets underlined.)

What about MULTiple CAPITal letters in a row? Cocoa text decides the identifier is fine when its characters form a word (as seen above) or when lowercased components form words (MULType and CAPITall are fine, but MULtype and CAPItall are underlined.)

Good heuristics.