From: headius@headius.com
To: ruby-core@ruby-lang.org
Subject: [ruby-core:103153] [Ruby master Bug#17771] String#start_with? should not construct MatchData or set $~
Date: Thu, 01 Apr 2021 18:08:03 +0000 (UTC) [thread overview]
Message-ID: <redmine.issue-17771.20210401180802.286@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-17771.20210401180802.286@ruby-lang.org
Issue #17771 has been reported by headius (Charles Nutter).
----------------------------------------
Bug #17771: String#start_with? should not construct MatchData or set $~
https://bugs.ruby-lang.org/issues/17771
* Author: headius (Charles Nutter)
* Status: Open
* Priority: Normal
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
I am working on making $~ more thread-safe in JRuby and came across this unexpected behavior:
```ruby
$ rvm ruby-3.0 do ruby -e '"foo".start_with?(/foo/); p $~'
#<MatchData "foo">
```
The `start_with?` method was added 11 years ago in https://bugs.ruby-lang.org/issues/3388 but I do not think the set of $~ was an intended feature. The `start_with?` method could be much faster and more thread-safe if it did not use the frame-local backref slot and did not allocate a MatchData.
Compare with `match?` which was added specifically (without MatchData or backref setting) to provide a fast way to check if a Regexp matches.
I propose that `start_with?` stop constructing MatchData, stop setting backref, and provide only its boolean result in the same way as `match?`.
--
https://bugs.ruby-lang.org/
next parent reply other threads:[~2021-04-01 18:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 18:08 headius [this message]
2021-04-01 18:13 ` [ruby-core:103154] [Ruby master Bug#17771] String#start_with? should not construct MatchData or set $~ headius
2021-04-01 18:25 ` [ruby-core:103155] " headius
2021-04-01 19:04 ` [ruby-core:103156] [Ruby master Feature#17771] " tom.enebo
2021-04-01 19:06 ` [ruby-core:103157] " headius
2021-04-02 10:28 ` [ruby-core:103176] " eregontp
2021-04-02 14:49 ` [ruby-core:103187] " marcandre-ruby-core
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-list from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.ruby-lang.org/en/community/mailing-lists/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=redmine.issue-17771.20210401180802.286@ruby-lang.org \
--to=ruby-core@ruby-lang.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).