Should we hire someone who writes C in Perl?

Asked 2009-06-09T06:20:42.937

57

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

Since my colleague didn't know Perl, he asked me for a critique of some code written (off-site) by that potential hire, so I had a look and told him my concerns (the main one was that it originally had no comments and it's not like we gave them enough time).

However, the code works so I'm loath to say no-go without some more input. Another concern is that this code basically looks exactly how I'd code it in C. It's been a while since I did Perl (and I didn't do a lot, I'm more a Python bod for quick scripts) but I seem to recall that it was a much more expressive language than what this guy used.

I'm looking for input from real Perl coders, and suggestions for how it could be improved (and why a Perl coder should know that method of improvement).

You can also wax lyrical about whether people who write one language in a totally different language should (or shouldn't be hired). I'm interested in your arguments but this question is primarily for a critique of the code.

The spec was to successfully process a CSV file as follows and output the individual fields:

User ID,Name , Level,Numeric ID
pax, Pax Morgan ,admin,0
gt,"  Turner, George" rubbish,user,1
ms,"Mark \"X-Men\" Spencer","guest user",2
ab,, "user","3"

The output was to be something like this (the potential hire's code actually output this):

User ID,Name , Level,Numeric ID:
   [User ID]
   [Name]
   [Level]
   [Numeric ID]
pax, Pax Morgan ,admin,0:
   [pax]
   [Pax Morgan]
   [admin]
   [0]
gt,"  Turner, George  " rubbish,user,1:
   [gt]
   [  Turner, George  ]
   [user]
   [1]
ms,"Mark \"X-Men\" Spencer","guest user",2:
   [ms]
   [Mark "X-Men" Spencer]
   [guest user]
   [2]
ab,, "user&qu



        
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                        It isn't dreadfully idiomatic Perl, but it isn't completely dreadful Perl either (though it could be much more compact).

Two warning bells - the shebang line doesn't include '-w' and there is neither 'use strict;' nor 'use warnings;'.  This is very old-style Perl; good Perl code uses both warnings and strict.

The use of old-style file handles is no longer recommended, but it isn't automatically bad (it could be code written more than 10 years ago, perhaps).

The non-use of regular expressions is a bit more surprising.  For example:

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

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


That could be written:

while ($line ne "") {
    $line =~ s/^\s+//;


This chops off all leading spaces using a regex, without making the code iterate around the loop.  A good deal of the rest of the code would benefit from carefully written regular expressions too.  These are a characteristically Perl idiom; it is surprising to see that they are not being used.

If efficiency was the proclaimed concern (reason for not using regexes), then the questions should be "did you measure it" and "what sort of efficiency are you discussing - machine, or programmer"?

Working code counts.  More or less idiomatic code is better.

Also, of course, there are modules Text::CSV and Text::CSV_XS that could be used to handle CSV parsing.  It would be interesting to enquire whether they are aware of Perl modules.



There are also multiple notations for handling quotes within quoted fields.  The code appears to assume that backslash-quote is appropriate; I believe Excel uses doubled up quotes:

"He said, ""Don't do it"", but they didn't listen"


This could be matched by:

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                            answered 2009-06-09T06:45:57.393
                            
                        
                        
                            
                                
                                
                            
                        
                        
                            
                            
                            
                                
                                
                            
                            
                        
                    
                
            
            
        

        
        
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