4 ms·

I'm interested to hear you say this. I teach this course, to students who mostly go on to do Java coding. I have several times run into an old student who tol

I'm interested to hear you say this. I teach this course, to students who mostly go on to do Java coding. I have several times run into an old student who told me that they never once used regexes after my class, either in school or in work.

manish_gill 11y ago
That is very surprising to hear. Regular expressions are used all over the place! I wouldn't want to work with a person who does not have at least the basic workings of Regex down pat.
iso8859-1 11y ago
One reason may be that practical regexes have so many extensions that you can't many of the usual tricks on them. http://stackoverflow.com/questions/6363397/how-to-tell-if-one-regular-expression-matches-a-subset-of-another-regular-expres http://stackoverflow.com/questions/6363397/how-to-tell-if-on...
- brudgers 11y ago
  I find it helpful to distinguish between "regular expressions" as something mathematical and "regexes" as nebulous more-than an NFA and less than a Turing complete grammar...DFA regex engines being the Platypus that proves the rule. As soon as you have backtracking and capture groups it's not a regular expression in the mathematical sense. These features make regexes more useful in many simple cases at the cost of making them harder to reason about in more difficult cases.
varlock 11y ago
I'm surprised - Did you ask them how do they search for patterns? Entries in log files, function definitions or usage in code, matching files in a shell?
- jimhefferon 11y ago
  > Did you ask them how do they search for patterns? Entries in log files, function definitions or usage in code, matching files in a shell? You know, I have. In some ways it is like communicating across cultures in that the question does not seem to make all that much sense to them. That I can tell, they don't ever search for patterns. The would look for that feature in their GUI log reading program, I suppose. Failing that, they would write code, 100% in Java I think, and I suppose that if they had to do what I would reach for a regex to do, they would write code to do it. (Is this what jwz means by "Now they have two problems," that they should do the job in code?) But, again, I don't think there is a real communication there. I'm not too sure what they mean and they look like they do not recognize the situations I ask about.

manish_gill 11y ago

That is very surprising to hear. Regular expressions are used all over the place! I wouldn't want to work with a person who does not have at least the basic workings of Regex down pat.

iso8859-1 11y ago

One reason may be that practical regexes have so many extensions that you can't many of the usual tricks on them. http://stackoverflow.com/questions/6363397/how-to-tell-if-one-regular-expression-matches-a-subset-of-another-regular-expres http://stackoverflow.com/questions/6363397/how-to-tell-if-on...

brudgers 11y ago
I find it helpful to distinguish between "regular expressions" as something mathematical and "regexes" as nebulous more-than an NFA and less than a Turing complete grammar...DFA regex engines being the Platypus that proves the rule. As soon as you have backtracking and capture groups it's not a regular expression in the mathematical sense. These features make regexes more useful in many simple cases at the cost of making them harder to reason about in more difficult cases.

varlock 11y ago

I'm surprised - Did you ask them how do they search for patterns? Entries in log files, function definitions or usage in code, matching files in a shell?

jimhefferon 11y ago
> Did you ask them how do they search for patterns? Entries in log files, function definitions or usage in code, matching files in a shell? You know, I have. In some ways it is like communicating across cultures in that the question does not seem to make all that much sense to them. That I can tell, they don't ever search for patterns. The would look for that feature in their GUI log reading program, I suppose. Failing that, they would write code, 100% in Java I think, and I suppose that if they had to do what I would reach for a regex to do, they would write code to do it. (Is this what jwz means by "Now they have two problems," that they should do the job in code?) But, again, I don't think there is a real communication there. I'm not too sure what they mean and they look like they do not recognize the situations I ask about.