From: marcandre-ruby-core@... Date: 2021-04-02T14:49:32+00:00 Subject: [ruby-core:103187] [Ruby master Feature#17771] String#start_with? should not construct MatchData or set $~ Issue #17771 has been updated by marcandre (Marc-Andre Lafortune). I also believe it is unintended behavior and should be removed. ---------------------------------------- Feature #17771: String#start_with? should not construct MatchData or set $~ https://bugs.ruby-lang.org/issues/17771#change-91262 * Author: headius (Charles Nutter) * Status: Open * Priority: Normal ---------------------------------------- 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 $~' # ``` 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/ Unsubscribe: