From: "sawa (Tsuyoshi Sawada)" <sawadatsuyoshi@...>
Date: 2013-09-29T18:35:42+09:00
Subject: [ruby-core:57464] [ruby-trunk - Feature #8948] Frozen regex


Issue #8948 has been updated by sawa (Tsuyoshi Sawada).


jwille,

My understanding with the case of string in your example is that the two strings would count as different strings, but for respective method calls would not create new strings. It would mean one of the string can be `"ab"` and the other a different string such as `"cd"`.

If that is what you intended for your regex examples, then there is no difference.
----------------------------------------
Feature #8948: Frozen regex
https://bugs.ruby-lang.org/issues/8948#change-42077

Author: sawa (Tsuyoshi Sawada)
Status: Feedback
Priority: Normal
Assignee: 
Category: 
Target version: 


=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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