From: eregontp@... Date: 2019-09-08T09:40:36+00:00 Subject: [ruby-core:94840] [Ruby master Feature#16150] Add a way to request a frozen string from to_s Issue #16150 has been updated by Eregon (Benoit Daloze). I also tried this version which always returns the same String for a given Symbol: ```diff diff --git a/string.c b/string.c index 05ce0ed8d6..f306c905bc 100644 --- a/string.c +++ b/string.c @@ -10866,7 +10866,7 @@ sym_inspect(VALUE sym) VALUE rb_sym_to_s(VALUE sym) { - return str_new_shared(rb_cString, rb_sym2str(sym)); + return rb_sym2str(sym); } ``` And that passes both test-spec and test-all, except this test which probably needs to be adapted: ``` [5/8] Test_StringCapacity#test_capacity_shared = 0.00 s 1) Failure: Test_StringCapacity#test_capacity_shared [/home/eregon/code/ruby/test/-ext-/string/test_capacity.rb:17]: <0> expected but was <26>. ``` I'll make a PR. ---------------------------------------- Feature #16150: Add a way to request a frozen string from to_s https://bugs.ruby-lang.org/issues/16150#change-81460 * Author: headius (Charles Nutter) * Status: Open * Priority: Normal * Assignee: * Target version: ---------------------------------------- Much of the time when a user calls to_s, they are just looking for a simple string representation to display or to interpolate into another string. In my brief exploration, the result of to_s is rarely mutated directly. It seems that we could save a lot of objects by providing a way to explicitly request a *frozen* string. For purposes of discussion I will call this to_frozen_string, which is a terrible name. This would reduce string allocations dramatically when applied to many common to_s calls: * Symbol#to_frozen_string could always return the same cached String representation. This method is *heavily* used by almost all Ruby code that intermingles Symbols and Strings. * nil, true, false, and any other singleton values in the system could similarly cache and return the same String object. * The strings coming from core types could also be in the fstring cache and deduplicated as a result. * User-provided to_s implementations could opt-in to caching and returning the same frozen String object when the author knows that the result will always be the same. A few ideas for what to call this: * `to_fstring` or `fstring` reflects internal the "fstring" cache but is perhaps not obvious for most users. * `to_s(frozen: true)` is clean but there will be many cases when the kwargs hash doesn't get eliminated, making matters worse. * `def to_s(frozen = false)` would be mostly free but may not be compatible with existing to_s params (like `Integer#to_s(radix)` This idea was inspired by @schneems's talk at RubyConf Thailand, where he showed significant overhead in ActiveRecord from Symbol#to_s allocation. -- https://bugs.ruby-lang.org/ Unsubscribe: