[ruby-core:96211] [Ruby master Feature#16377] Regexp literals should be frozen
From:
jean.boussier@...
Date:
2019-12-12 10:09:22 UTC
List:
ruby-core #96211
Issue #16377 has been updated by byroot (Jean Boussier).
> just for the sake of Communicating the Holy Gospel of Immutability?
Please put ideological thoughts on me, that's not a good basis for debate.
> Regexp literals are not deduplicated in the same sense as frozen string literals; one /abc/ is independant from another /abc/
And if they were frozen, they could be.
> so we're not actually leaking "global" state
On a particular callsite it does.
> Or, more realistically, what about something like this?
```ruby
class Regexp
@@analyses = {}.compare_by_identity
def analyze
@@analyses[self] ||= RegexpAnalyzer.analyze_performance_issues(self)
end
end
```
----------------------------------------
Feature #16377: Regexp literals should be frozen
https://bugs.ruby-lang.org/issues/16377#change-83103
* Author: byroot (Jean Boussier)
* Status: Open
* Priority: Normal
* Assignee:
* Target version:
----------------------------------------
The following script:
```ruby
def mutate
re = /foo/
state = re.instance_variable_get(:@state)
re.instance_variable_set(:@state, state.to_i + 1)
state
end
3.times do
p mutate
end
```
Output this:
```
nil
1
2
```
IMHO, you shouldn't be able to mutate an unduplicated literal.
GitHub pull request: https://github.com/ruby/ruby/pull/2705
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