Creating and calling a default proc is a waste of time, and Cramming everything into one line using tortured constructs doesn't make the code more efficient--it just makes the code harder to understand.
The nature of this "answer" is a comment in response to another answer. But because of the limitations SO puts on comments (very short length, no multi-line code snippets), comment feature could not actually be used, so this user resorted to "abusing" answer feature to post their comment instead.
See