Regex character "$" doesn't mean "end-of-string"

Post by influx » Wed, Mar 20, 2024, 2:50 PM UTC

ydant wrote: post #98

xlii wrote: post #8

Regexp was one of the first things I truly internalized years ago when I was discovering Perl (which still lives in a cozy place in my heart due to a lovely “Camel” book). Today most important bit of information is knowledge that implementations differ and I made a habit of pulling reference sheet for a thing I work with. E.g. Emacs Regexp annoyingly doesn’t have word in form of “\w” but uses “\s_-“ (or something no…

Exactly the same here, re: Perl. My brain thinks in Perl's regex language and then I have to translate the inconsistent bits to the language I'm using. Especially in the shell - I'm way more likely to just drop a perl into the pipeline instead of trying to remember how sed/grep/awk (GNU or BSD?) prefer their regex.

Post by lcnPylGDnU4H9OF » Wed, Mar 20, 2024, 2:54 PM UTC

richardwhiuk wrote: post #195

perlgeek wrote: post #68

Raku (formerly Perl 6) has picked ^ and $ for start-of-string and end-of-string, and has introduced ^^ and $$ for start-of-line and end-of-line. No multi line mode is available or necessary. (There's also \h for horizontal and \v for vertical whitespace) That's one of the benefits of a complete rethink/rewrite, you can learn from the fact that the old behavior surprised people.

Think I would have picked exactly the reverse (i.e. ^^ being more "starty" than "^").

Post by kstrauser » Wed, Mar 20, 2024, 3:00 PM UTC

usrusr wrote: post #32

telotortium wrote: post #15

Earlier quoted context omitted.

Languages invented after Perl will generally use some flavor of Perl regex syntax, but there are always some minor differences. The issue of the meaning of `$` and changing it via multi-line mode is usually consistent though.

I like to think of "whatever browsers do in js" as an updated common baseline. Whatever your regex engine does, describe it as a delta to the js precedent. That thing is just so ubiquitous. I do wonder though what's the highest number of different regex syntaxes I've ever encountered (perhaps written?) within a single line: bash, grep and sed are never not in a "hold my beer" mood!

Post by mwpmaybe » Wed, Mar 20, 2024, 3:08 PM UTC

pizzafeelsright wrote: post #204

xlii wrote: post #8

Regexp was one of the first things I truly internalized years ago when I was discovering Perl (which still lives in a cozy place in my heart due to a lovely “Camel” book). Today most important bit of information is knowledge that implementations differ and I made a habit of pulling reference sheet for a thing I work with. E.g. Emacs Regexp annoyingly doesn’t have word in form of “\w” but uses “\s_-“ (or something no…

How did you internalize it? Perl looks like cat keyboarding.

Post by mwpmaybe » Wed, Mar 20, 2024, 3:13 PM UTC

usrusr wrote: post #32

telotortium wrote: post #15

Earlier quoted context omitted.

Languages invented after Perl will generally use some flavor of Perl regex syntax, but there are always some minor differences. The issue of the meaning of `$` and changing it via multi-line mode is usually consistent though.

I like to think of "whatever browsers do in js" as an updated common baseline. Whatever your regex engine does, describe it as a delta to the js precedent. That thing is just so ubiquitous. I do wonder though what's the highest number of different regex syntaxes I've ever encountered (perhaps written?) within a single line: bash, grep and sed are never not in a "hold my beer" mood!