Says the guy who made no attempt at his own problem and couldn't even contrive a case where it would matter.

No less than I'd expect from a web developer. Don't you have to go import another 400 libraries so you can copy/paste one more function or something?

You didn't realize "regular expression" and even "PCRE" means something slightly different in almost every language until just now did you?

Actually I'd like to see you offer a reason that isn't nullified by "not all possible DNS entries exist".

You don't get to use overflows or other escapes as an excuse, I already mentioned those.

A normal person would validate that it doesn't overflow or otherwise break their code.

A shitty programmer would sperg out about how to make a single perfect line that still fails anyway, and not even realize not every regular expression feature works the same or is supported in every implementation of regular expressions.

You didn't even specify what type of regex. Since it's possible to have a url that validates but doesn't exist or is otherwise unreachable, I'm at a loss for why anyone would care unless you run a registrar.

Valid characters in DNS request specification. That's it.

If you want to define a DNS response for "server" then "server" is now a valid URL.

It's the processor part of a circuit, and you've got a piece that lets you connect to a cellular network which might make it good for remote control or alerts.

It does the same stuff the pi does, read pin voltages and turn pins on/off just without being a full computer.

That's also true of is this and is not this