When I post a complete, runnable piece of code, I add the usual boilerplate. When I correct only a few lines of the OP's code, I don't.

I find it rather important to include the use 5.010; when I use say (which I do a lot, actually) in my examples, because the error message is often quite bad when you forget to include the pragma (often it complains that there is no method say, because perl parsed it as indirect method syntax).

And newcomers already have enough to struggle with, I don't want to increase their cognitive load by using a convenience subroutine that then makes their live harder.