From: ko1@...
Date: 2015-08-21T05:56:12+00:00
Subject: [ruby-core:70498] [Ruby trunk - Feature #8948] Frozen regex

Issue #8948 has been updated by Koichi Sasada.


A patch is small.

```diff
Index: re.c
===================================================================
--- re.c	(revision 51650)
+++ re.c	(working copy)
@@ -2548,6 +2548,8 @@
     if (!re->ptr) return -1;
     RB_OBJ_WRITE(obj, &re->src, rb_fstring(rb_enc_str_new(s, len, enc)));
     RB_GC_GUARD(unescaped);
+
+    rb_obj_freeze(obj);
     return 0;
 }
 
```

But I got many failures on rubyspec.
https://gist.github.com/ko1/da52575de115c928ce4a


----------------------------------------
Feature #8948: Frozen regex
https://bugs.ruby-lang.org/issues/8948#change-53898

* Author: Tsuyoshi Sawada
* Status: Assigned
* Priority: Normal
* Assignee: Yukihiro Matsumoto
----------------------------------------
=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



-- 
https://bugs.ruby-lang.org/