Back at university, there was a big rubber stamp reading "ABSTRACTION VIOLATION" that the SICP teaching assistants would use to mark problem set solutions as in

Back at university, there was a big rubber stamp reading "ABSTRACTION VIOLATION" that the SICP teaching assistants would use to mark problem set solutions as incorrect if they violated interface abstractions. Using a QString to represent a file path shoves display constraints down into the lowest level Qt file handling routines. It should have had a FilePath class used for representing file paths nearly everywhere, with a toString or to_string member function for display purposes.