My answer was that you can never really know Perl.
This being said, I have:
- Read a book on Perl (many books, in fact)
- Written a book on Perl (yes, written one, but, well, on Perl 6 in fact, dunno if this counts; but I have also written many large tutorials on Perl 5)
- not contributed to the Perl source code (I doubt I'd be able to do so)
- Debugged someone else's script (many times, including on various forums such as PM)
- Played Perl Golf (yes, but only a little bit, I'm not really a great fan of that, but I like to write good concise code)
- Used regular expressions to save the day (sure, a lot)
- Used Perl for a certain amount of time (about 15 years by now)
- Invested a certain amount of man-hours in learning Perl (sure, a fairly large amount of man-hours, most of which on my personal time)
- Visited at least x Perl related events (yes, quite a number of them)
- (Co)maintain at least x active (up-river) CPAN modules (well, only one)
- Forgotten you were not Larry Wall (oh, no, this I can't forget)
- One can never truly know Perl (yes, I think so; at least, I'm pretty sure I won't ever truly know Perl, but that does not prevent me from using it successfully)