[ruby-core:77921] [Ruby trunk Feature#12901] Anonymous functions without scope lookup overhead
From:
richard.schneeman@...
Date:
2016-11-04 16:54:31 UTC
List:
ruby-core #77921
Issue #12901 has been reported by Richard Schneeman.
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Feature #12901: Anonymous functions without scope lookup overhead
https://bugs.ruby-lang.org/issues/12901
* Author: Richard Schneeman
* Status: Open
* Priority: Normal
* Assignee:
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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.
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