From: ko1@... Date: 2020-06-16T08:11:57+00:00 Subject: [ruby-core:98821] [Ruby master Feature#12901] Anonymous functions without scope lookup overhead Issue #12901 has been updated by ko1 (Koichi Sasada). I read this ticket and several comments: ## `Proc#call` calling performance The performance gap is because of optimization level. We didn't optimize `Proc#call` enough, so the capturing is not a reason. ## capturing outer-scope (making closure) We will introduce `Proc#isolate` which creates a Proc but accessing outer scope is not allowed for the parallel execution (Guild/Ractor). So we can make such Proc. However, the normal Proc is created before calling `Proc#isolate` (`Proc.new{...}.isolate`), So Proc capturing overhead is not avoided. `Proc.new(isolate: true){ ... }` can avoid it. New syntax BTW `self` is same as outer-scope. Guild/Ractor replaces it using `instance_eval` technique. ---------------------------------------- Feature #12901: Anonymous functions without scope lookup overhead https://bugs.ruby-lang.org/issues/12901#change-86184 * Author: schneems (Richard Schneeman) * Status: Open * Priority: Normal ---------------------------------------- Right now if you are writing performance sensitive code you can get a performance bump by not using anonymous functions (procs, lambdas, blocks) due to the scope lookup overhead. https://twitter.com/apotonick/status/791167782532493312?lang=en I would like to be able to create an anonymous function and specify I don't need it to perform the lookup when called. I am thinking that this code: ~~~ Proc.new(scope: false) {|var| puts var } ~~~ Would be the equivalent of ~~~ def anon(var) puts var end ~~~ If you call it while trying to access something from outside of the scope it would error ~~~ var = "hello" Proc.new(scope: false) { puts var }.call # => NameError: undefined local variable or method `var' for main:Object ~~~ An example of a case where this could be used is found in https://github.com/rails/sprockets/pull/417. In this case we are getting rid of anonymous functions in favor of a method created with refinements. This solution works but it was not an obvious optimization. It would be convenient to have a syntax for defining anonymous functions that do not need access to caller scope. -- https://bugs.ruby-lang.org/ Unsubscribe: