Some people, when confronted with a problem, think “I know, I’ll use regular expressions.” Now they have two problems.
Regex really isn’t that bad when using named capture groups.
Oh yeah they definitely have uses, but there’s a real tendency for people to go a bit crazy with them. Complex regexen aren’t exactly readable, there’s all kinds of fun performance gotchas, there’s sometimes other tools/algorithms that are more suitable for the task, and sometimes people try to use them to eg. parse HTML because they don’t know that it is literally impossible to use regular expressions to parse languages that aren’t regular
It’s entirely possible to parse HTML in PCRE. You shouldn’t, but it is possible. The language stopped being strictly regular a long time ago and is entirely capable of doing it.
Oh yeah, extensions which make them non-regular definitely can make it possible, but just because it’s now somewhat possible with some regex engines doesn’t mean it’s a good idea
it is literally impossible to use regular expressions to parse languages that aren’t regular
It’s impossible to parse the whole syntax tree, but that doesn’t mean you can’t get the subset you’re interested in.
Blasphemy, that’s not regex that’s just fancy grep
I don’t actually know whether POSIX grep would support named groups :o
Don’t have you have to use the
-Pflag?which is just perl mode
Regex feels distinctly eldritch to me. Like, a lot of computing knowledge feels like magic, but regex feels like the kind of magic you get by consorting with dark forces
regex feels like the kind of magic you get by consorting with dark forces
AKA reading the manual.
Im a good christian boy thats why I refuse to read the manual
Named groups are nice but can I please define a group more than once because maybe I want to group my data and consolidate values in a logical way without you complaining I have already used a group previously. I know I did, I’m the one telling you, now capture it twice!
I really like this approach for doing non trivial regex https://github.com/VerbalExpressions
const tester = VerEx() .startOfLine() .then('http') .maybe('s') .then('://') .maybe('www.') .anythingBut(' ') .endOfLine();I don’t. It may look less like line noise, but it doesn’t unravel the underlying complexity of what it does. It’s just wordier without being helpful.
Edit: also, these alternative syntaxes tend to make some easy cases easy, but they have no idea what to do with more complicated cases. Try making nested capture groups with these, for instance. It gets messy fast.
Can you actually name capture groups, or this means how you can refer to them by number?
You can use backreferences
\1 \2etc. but you can also give them names explicitly.
it looks like this:(?<name>inner-regex)
Some flavors support it, kotlins doesn’t apparently.In modern languages you can name them with labels as well yes. Not sure about the syntax right now. Something like (?label:…) I think
I don’t see the problem. But that’s probably because my goto-language is perl.
