Should we hire someone who writes C in Perl? [closed]

Answer 1

I advise people to never hire Perl programmers, or C programmers, or Java programmers, and so on. Just hire good people. The programmers who I've hired to write Perl were also skilled in various other languages. I hired them because they were good programmers, and good programmers can deal with multiple languages.

Now, that code does look a lot like C, but I think it's fine Perl too. If you're hiring a good programmer, with a little Perl practice under his belt he'll catch up just fine. People are complaining about the lack of regexes, which would make things simpler in ancillary areas, but I wouldn't wish on anyone a regex solution on parsing that dirty CSV data. I wouldn't want to read it or maintain it.

I often find that the reverse problem is more troublesome: hire a good programmer who writes good Perl code, but the rest of the team only knows the basics of Perl and can't keep up. This has nothing to do with poor formatting or bad structure, just a level of skill with advanced topics (e.g. closures).

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Things are getting a bit heated in this debate, so I think I should explain more about how I deal with this sort of thing. I don't see this as a regex / no-regex problem. I wouldn't have written the code the way the candidate did, but that doesn't really matter.

I write quite a bit of crappy code too. On the first pass, I'm usually thinking more about structure and process than syntax. I go back later to tighten that up. That doesn't mean that the candidate's code is any good, but for a first pass done in an interview I don't judge it too harshly. I don't know how much time he had to write it and so on, so I don't judge it based on something I would have had a long time to work on. Interview questions are always weird because you can't do what you'd really do for real work. I'd probably fail a question about writing a CSV parser too if I had to start from scratch and do it in 15 minutes. Indeed, I wasted more than that today being a total bonehead with some code.

I went to look at the code for Text::CSV_PP, the Pure Perl cousin to Text::CSV_XS. It uses regular expressions, but a lot of regular expressions that handle special cases, and in structure isn't that different from the code presented here. It's a lot of code, and it's complicated code that I hope I never have to look at again.

What I tend to disfavor are interview answers that only address the given input. That's almost always the wrong thing to do in the real world where you have to handle cases that you may not have discovered yet and you need the flexibility to deal with future issues. I find that missing from a lot of answers on Stackoverflow too. The thought process of the solution is more telling to me. People become skilled at a language more easily than they change how they think about things. I can teach people how to write better Perl, but I can't change their wetware for the most part. That comes from scars and experience.

Since I wasn't there to see the candidate code the solution or ask him follow-up questions, I won't speculate on why he wrote it the way he did. For some of the other solutions I've seen here, I could be equally harsh in an interview.

A career is a journey. I don't expect everyone to be a guru or to have the same experiences. If I write-off people because they don't know some trick or idiom, I'm not giving them the chance to continue their journey. The candidate's code won't win any prizes, but apparently it was enough to get him into the final three for consideration for an offer. The guy got up there and tried, did much better than a lot of code I've seen in my life, and that's good enough for me.

Answer 2

I'd say his code is an adequate solution. It works, doesn't it? And there's an advantage to maintainability by writing "longhand" instead of in as few characters of code as you can.

The motto of Perl is "There's More Than One Way To Do It." Perl doesn't really get on your case about coding style, as some languages do (I like Python too, but you've got to admit that people can get kind of snobbish when evaluating whether code is "pythonic" or not).

Answer 3

The fact that he hasn't used a single piece of regex in the code should make you ask him a lot of questions about why he did write like that.

Maybe he's Jamie Zawinski or a fan and he didn't want to have more problems?

I'm not necessarily saying that the whole parsing should be a huge amount of unreadable CSV parsing regex like ("([^"]*|"{2})*"(,|$))|"[^"]*"(,|$)|[^,]+(,|$)|(,) or one of the many similar regex around, but at least to traverse the lines or instead of using substring().

Answer 4

An obvious question might be, if you don't use Perl at your company in the first place, does it matter how pretty his Perl code is?

I'm not sure the elegance of his Perl code says much about his skills in whatever language you're actually using.

Answer 5

One of my colleagues recently interviewed some candidates for a job and one said they had very good Perl experience.

If this person thinks he has very good Perl experience and he writes Perl like this, he is probably a victim of the Dunning-Kruger effect.

So, that's a no-hire.

Answer 6

Just the initial block indicates that he has missed the fundamentals about Perl.

    while ($line ne "") {
    # Skip spaces and start with empty field.

    if (substr ($line,0,1) eq " ") {
        $line = substr ($line,1);
        next;
    }

That should at least be written using a regular expression to remove leading white space. I like the answer from jrockway best, modules rock. Though I would have used regular expressions to do it, something like.

#!/usr/bin/perl -w
#
# $Id$
#

use strict;

open(FD, "< qq.in") || die "Failed to open file.";
while (my $line = <FD>) {
    # Don't like chomp.
    $line =~ s/(\r|\n)//g;
    # ".*?[^\\\\]"  = Match everything between quotations that doesn't end with
    # an escaped quotation, match lazy so we will match the shortest possible.
    # [^",]*?       = Match strings that doesn't have any quotations.
    # If we combine the two above we can match strings that contains quotations
    # anywhere in the string (or doesn't contain quotations at all).
    # Put them together and match lazy again so we can match white-spaces
    # and don't include them in the result.
    my $match_field = '\s*((".*?[^\\\\]"|[^",]*?)*)\s*';
    if (not $line =~ /^$match_field,$match_field,$match_field,$match_field$/) {
        die "Invalid line: $line";
    }
    # Put values in nice variables so we don't have to deal with cryptic $N
    # (and can use $1 in replace).
    my ($user_id, $name, $level, $numeric_id) = ($1, $3, $5, $7);
    print "$line\n";
    for my $field ($user_id, $name, $level, $numeric_id) {
        # If the field starts with a quotation,
        # strip everything after the first unescaped quotation.
        $field =~ s/^"(.*?[^\\\\])".*/$1/g;
        # Now fix all escaped variables (not only quotations).
        $field =~ s/\\(.)/$1/g;
        print "   [$field]\n";
    }
}
close FD;