From: "Eregon (Benoit Daloze)" <redmine@...>
Date: 2013-09-30T17:25:34+09:00
Subject: [ruby-core:57475] [ruby-trunk - Feature #8948] Frozen regex


Issue #8948 has been updated by Eregon (Benoit Daloze).


ko1 (Koichi Sasada) wrote:
> 2.2 matter?

2.1 would make sense to me, so it goes along with other frozen literals.

> Anyone set instance variable for each regexp? :)

I highly doubt it.
----------------------------------------
Feature #8948: Frozen regex
https://bugs.ruby-lang.org/issues/8948#change-42089

Author: sawa (Tsuyoshi Sawada)
Status: Feedback
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: syntax
Target version: next minor


=begin
I see that frozen string was accepted for Ruby 2.1, and frozen array and hash are proposed in https://bugs.ruby-lang.org/issues/8909. I feel there is even more use case for a frozen regex, i.e., a regex literal that generates a regex only once. It is frequent to have a regex within a frequently repeated portion of code, and generating the same regex each time is a waste of resource. At the moment, we can have a code like:

    class Foo
      RE1 = /pattern1/
      RE2 = /pattern1/
      RE3 = /pattern1/
      def classify
        case self
        when RE1 then 1
        when RE2 then 2
        when RE3 then 3
        else 4
        end
      end
    end

but suppose we have a frozen `Regexp` literal `//f`. Then we can write like:

    class Foo
      def classify
        case self
        when /pattern1/f then 1
        when /pattern1/f then 2
        when /pattern1/f then 3
        else 4
        end
      end
    end

=end


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