From: "kou (Kouhei Sutou) via ruby-core" Date: 2026-06-04T01:32:49+00:00 Subject: [ruby-core:125619] [Ruby Feature#19315] Lazy substrings in CRuby Issue #19315 has been updated by kou (Kouhei Sutou). Dan0042 (Daniel DeLorme) wrote in #note-26: > I agree that completely deprecating RSTRING_PTR might not be strictly necessary, but for the sake of a smooth migration, I highly recommend introducing RSTRING_CSTR as an alias for the new, NUL-terminated RSTRING_PTR behavior. I don't object the idea but `CSTR` may not be a good name. Because we already have `StringValueCStr()` that not only ensures the target content is `\0` terminated but also ensures the target content doesn't include `\0`. `RSTRING_CSTR()` doesn't check whether `\0` is included in the target content or not. ---------------------------------------- Feature #19315: Lazy substrings in CRuby https://bugs.ruby-lang.org/issues/19315#change-117469 * Author: Eregon (Benoit Daloze) * Status: Open ---------------------------------------- CRuby should implement lazy substrings, i.e., "abcdef"[1..3] must not copy bytes. Currently CRuby only reuse the char* if the substring is until the end of the buffer. But it should also work wherever the substring starts and ends. Yes, it means RSTRING_PTR() might need to allocate to \0-terminate, so be it, it's worth it. There is already code for this (`SHARABLE_MIDDLE_SUBSTRING`), but it's disabled by default and `RSTRING_PTR()` needs to be changed to deal with this. It seems a good idea to introduce a variant of `RSTRING_PTR` which doesn't guarantee \0-termination, so such callers can then use the existing bytes always without copy. There are countless workarounds for this missing optimization, all not worth it with lazy substring and all less readable: * https://bugs.ruby-lang.org/issues/19314 * https://bugs.ruby-lang.org/issues/18598#note-3 * https://github.com/ruby/net-protocol/pull/14 * Manual lazy substrings which track string + index + length * More but I don't remember all now, feel free to comment or link more urls/tickets. -- https://bugs.ruby-lang.org/ ______________________________________________ ruby-core mailing list -- ruby-core@ml.ruby-lang.org To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/