From: headius@... Date: 2016-11-08T07:15:53+00:00 Subject: [ruby-core:78048] [Ruby trunk Feature#12901] Anonymous functions without scope lookup overhead Issue #12901 has been updated by Charles Nutter. In https://github.com/rails/sprockets/pull/417 I showed that JRuby can be significantly faster if the proc is stuffed into a `define_method` method. This is because we optimize `define_method` blocks to behave exactly like a plain method (with no closure state, etc) if we can statically determine it does not access its captured scope. This feature could be generalized in any implementation as a `function` kernel method. When creating a `function` a Ruby impl would check if any captured state was accessed. This includes variables like `$~`. If that state is accessed, it could either be a warning or an error. If it is not accessed, then the closure body would be "unrooted" from its captured scope and turned into a flat method. Much of the overhead shown here would go away. ---------------------------------------- Feature #12901: Anonymous functions without scope lookup overhead https://bugs.ruby-lang.org/issues/12901#change-61402 * 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: