Depends on the question. If it is about 1 line of code then the chatterbox is probably a good choice. If you are talking about 40 lines of code then make a node with the question.

Basically if you can't fit the code in one line on the chatterbox it is probably too big. You could use your scratchpad if you prefer to not make a node.

Update. If you do have questions about your code please try to title them well. Read How do I compose an effective node title?. The title "very tight perl syntax" is ambiguous and does not provide insight into what you are really asking.