From: jean.boussier@... Date: 2019-09-26T13:37:32+00:00 Subject: [ruby-core:95109] [Ruby master Feature#16150] Add a way to request a frozen string from to_s Issue #16150 has been updated by byroot (Jean Boussier). @nobu Yes that's what I had in mind, but then from what I understand it means we have to lookup the fstring table every time rather than just return a existing pointer. So it's not really an optimisation, is it? ---------------------------------------- Feature #16150: Add a way to request a frozen string from to_s https://bugs.ruby-lang.org/issues/16150#change-81743 * Author: headius (Charles Nutter) * Status: Assigned * Priority: Normal * Assignee: Eregon (Benoit Daloze) * 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: