Regular Expressions! With all the esoteric differences due to dialects, multiple platforms, multiple languages; I have refused to co-opt my brainspace with them. They are beautiful and powerful. They are awesome. I will never learn them. When I need them, I need a book, a google or a friend.
Understanding finite state machines, whether you are the consummate computer scientist who remembers that term from her first course in discrete mathematics or the self-taught hacker who gets the idea by slogging through a regex reference, is a fundamental tool for applying logic to data. Actually understanding them is more important than being able to search Google, find a book or ask a friend because not all regex solutions to a given problem are created equal. Any monkey can paste in a handful of passable expressions, glued together with bloated, unsightly, difficult to work with code, that does unnecessary data transformations and I/O to compensate. But someone who knows regex well can often write a single, svelt expression that speeds through all of that. Especially when you're dealing with big data, the cycles and the I/O start to add up. I'd be much happier to find a complex regex in someone else's code, with a concise but poignant comment, rather than an extra fifty lines of unnecessary loops and string manipulations.
I always ask a fairly complicated regex question during interview. You probably shouldn't apply for the open position at my workplace ;)
Complicated regex during the interview is no different than complicated code during the interview. It doesn't prove anything because we have tools like IDE and search. I could come up with my own esoteric reasons for wanting someone to be deep in binary logic, or know exactly how DNS works. but at the end of the day these are tools. If someone is aware of the various tools and can use them enough to accomplish the tasks, then really, that is enough. All I want in a recruit is the passion for learning, I don't care if they know any regex, as long as they are willing to learn.
I agree, but not across the board. When I do ask a technical, test-like question during an interview, I expressly refrain from trying to trick or find the limits of a candidates knowledge. While there is a component of wanting to make sure he or she is not lying to me about some skill listed on the resume, and I certainly would be glad to see that the candidate can competently solve the problem, I'm most interested in seeing if he or she can get stuck and ask for help. Anyone who can admit not knowing, and rather than give up with an "I don't know" but instead seek to still accomplish a goal by asking for help in an interview will pique my interest, not only for displaying an excellent work ethic, but also giving me the chance to travel through his or her problem solving and thought process. You want to hire for an entry level devops position, sure, no test questions, and focus on that passion for learning. You want to fill a senior or supervising devops position, that person must be intimately familiar with regex because she will be the person teaching the willing entry level guy.
Yeah, totally get that if you are hiring a senior position then knowing the common tools is a requirement. You are hiring a master of their craft, not a journeyman. I took your original post to mean you do that for all hires :)
Definitely sounds like one I'll avoid, thanks!
I'm pretty familiar with regex concepts and basic usage from a course I took in Perl, but it seems like every time I use them in a program my knowledge is obscured by the various discrepancies between languages.
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