Issue #17145 has been updated by Eregon (Benoit Daloze).


A dynamic call to `freeze` causes extra calls, and needs checks that it was indeed frozen.
So for efficiency I think it would be better to mark as frozen internally without a call to `freeze` on every value.

Also a leaf `freeze` call could technically mutate the object referencing it and e.g., add a new @ivar, which would make it complicated to ensure everything is frozen
(would need to mark as shallow-frozen first to prevent that, and only as deep-frozen once all contained values are deeply-frozen).

Is there a compelling reason to call a user-defined `freeze` for every value?

----------------------------------------
Feature #17145: Ractor-aware `Object#deep_freeze`
https://bugs.ruby-lang.org/issues/17145#change-87420

* Author: marcandre (Marc-Andre Lafortune)
* Status: Open
* Priority: Normal
----------------------------------------
I'd like to propose `Object#deep_freeze`:

Freezes recursively the contents of the receiver (by calling `deep_freeze`) and
then the receiver itself (by calling `freeze`).
Values that are shareable via `Ractor` (e.g. classes) are never frozen this way.

```ruby
# freezes recursively:
ast = [:hash, [:pair, [:str, 'hello'], [:sym, :world]]].deep_freeze
ast.dig(1, 1) # => [:str, 'hello']
ast.dig(1, 1).compact! # => FrozenError

# does not freeze classes:
[[String]].deep_freeze
String.frozen? # => false

# calls `freeze`:
class Foo
  def freeze
    build_cache!
    puts "Ready for freeze"
    super
  end
  # ...
end
[[[Foo.new]]].deep_freeze # => Outputs "Ready for freeze"
```


I think a variant `deep_freeze!` that raises an exception if the result isn't Ractor-shareable would be useful too:

```ruby
class Fire
  def freeze
    # do not call super
  end
end

x = [Fire.new]
x.deep_freeze! # => "Could not be deeply-frozen: #<Fire:0x00007ff151994748>"
```



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