[ruby-core:113073] [Ruby master Feature#19555] Allow passing default options to `Data.define`

Issue #19555 has been updated by FlickGradley (Nick Bradley).


I'm curious about this as well. Would it make sense to have a separate method `.with_defaults`, that checks the mutability (i.e. `.frozen?`) of its arguments?

If the intention is for Data to be "deeply" immutable, I could see this making sense. Then again, I'm not sure if there is a way to detect mutability of all objects "belonging to" a given parent object. I guess if there were such a way, it would have been included in Data already, as a way to enforce its immutability.

Perhaps this sort of thing should exist in ActiveSupport instead, or as a gem, since its immutability checking cannot be guaranteed to work in all cases (but could be written to work for most). This is effectively the same problem as Python has with mutable default arguments.

----------------------------------------
Feature #19555: Allow passing default options to `Data.define`
https://bugs.ruby-lang.org/issues/19555#change-102606

* Author: p8 (Petrik de Heus)
* Status: Open
* Priority: Normal
----------------------------------------
Defining a subclass of `Data` with default attributes can currently be done by overriding `intialize`:
```ruby
class Point < Data.define(:x, :y, :z)
  def initialize(x:, y:, z: 0) = super
end

p Point.new(1, 2)
#=> #<data Point x=1, y=2, z=0>
```

It would be nice if we could do it in `define` as well:

```ruby
Point = Data.define(:x, :y, z: 0)
```



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