From: headius@... Date: 2016-11-08T07:18:17+00:00 Subject: [ruby-core:78049] [Ruby trunk Feature#12901] Anonymous functions without scope lookup overhead Issue #12901 has been updated by Charles Nutter. I did not make clear what I was proposing. I do like the keyword idea, but I think I'd prefer a specific method like `function`: ```ruby function { ... } ``` Like `define_method` in JRuby, this would be an indicator that we explicitly want an unrooted body of code that acts like a pure function without any captured, mutable state. ---------------------------------------- Feature #12901: Anonymous functions without scope lookup overhead https://bugs.ruby-lang.org/issues/12901#change-61403 * Author: Richard Schneeman * Status: Open * Priority: Normal * Assignee: ---------------------------------------- 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: