From: jean.boussier@... Date: 2019-09-29T12:29:27+00:00 Subject: [ruby-core:95145] [Ruby master Feature#16150] Add a way to request a frozen string from to_s Issue #16150 has been updated by byroot (Jean Boussier). > However it's still not safe to modify it since it would modify the original string too. IMHO that's two different use cases. Either: - You want to be sure not to mutate the string, then you use `.dup` - You don't care about mutating the original string, you just want to minimize allocations, then you use `+@`. It's similar with `freeze` and `-@`. Either: - You simply want to prevent the string from being mutated, you use `.freeze` - You know you're going to hold on that string and want to optimize memory retention, you use `-@`. > How about making String#+ and #- without argument behave like #+@ and #-@ respectively, so that we can write: IMHO `.-` and `.+` is not very elegant. Proper method names explaining the intent would be preferable. - `-@` could be `dedup`, or `deduplicate`. - `+@` could be `mutable` or `mut`. ---------------------------------------- Feature #16150: Add a way to request a frozen string from to_s https://bugs.ruby-lang.org/issues/16150#change-81784 * Author: headius (Charles Nutter) * Status: Closed * 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: