BrowserUk sweetie, just so you know, GrandFather has helped me a lot over the years, so he kind of knows my quirks. What you saw as a knee-jerk reaction, was him seeing me saying something (in this case "faster") which is more than likely a alarm bell in his head actually. I am known to try to prematurely optimize my code. There are a few people on here who have told me not to do it, but I still do anyway. He chides me, I think, because he wants to remind me of one of my bad habits. Now you know about it, I am sure you will more than likely gently nudge me now and again if you see me doing it in the future.

As to my motivation to empty over delete, it is quite simple. I read in delete's doc "But both of these are slower than just assigning the empty list or undefining %HASH or @ARRAY:", so I looked at the suggestion below it, and used it instead. I didn't do any fancy testing (since I don't get testing as you know it) or whatever profiling is. (I think GrandFather was also trying, again, to push me into teaching myself testing which I tend to avoid because of the complexity of it. That is another discussion for another time.)

Now, would you please do me a teeny tiny favor and expand your abbreviations (AV*, HV*, and GCs)? I don't want to get it wrong in my head.

You can relax. GrandFather and others may look like they are coming on strong with their opinions to me, and most likely, it is to push me into the right direction when I appear bound and determined to go wrong. (In some rare cases their pushing worked actually.) So sit back and have a cookie. :)

I really don't want to get into a long debate about this but:

Because you are telling her, how she should program her code.

Isn't that in large part what Perlmonks is about? Or at least (because there is no code involved in this) offering well meant guidance.

And, (BTW) assuming (arrogantly) that she hasn't/didn't already profile both possibilities and choose appropriately.

Well, no actually. LA said "I thought about using delete, however the doc suggested emptying the lists would be faster.". No code involved. No test to see if there was a real issue. No consideration of which implementation might be easier to understand and maintain.

No attempt to help her. Just see the word (fast/er/est) and knee-jerk into patronizing dick mode.

Well, no actually. The advice offered was targeting the initial focus on speed instead of code clarity. Shaving a few micro seconds off something that only happens a few hundred times per execution of the script is almost certainly irrelevant.

In this particular case the code difference is likely to be small, but as a general thing concern over "the best way" can either make it almost impossible to make progress, or lead to very hard to maintain code that causes grief for ever. At $work an early coding decision for a C++ string object stores the actual string in a fashion that the debugger can't easily get at. At the time that probably made some string manipulations very slightly faster. Now compiler improvements mean that there is likely no performance advantage, but we get a major debugging disadvantage every time we want to see the contents of a string variable. The application using the string class does very little string manipulation so there is no performance improvement seen by users. The cost in developer time of that decision probably amounts to thousands of dollars.

So, I stand by my advice to LA and anyone else who bothers to read this far: Make it work first, then make it faster if you need to.