Freeze attributes belonging to Dry::Types::Value objects? about dry-types HOT 9 CLOSED

bump :)

from dry-types.

I might add a separate issue for this, but I think that Dry::Types::Struct objects should also change their behavior such that attribute values are duplicated upon instantiation:

require 'dry/types'

class Name < Dry::Types::Struct
  attribute :first, 'strict.string'
  attribute :last,  'strict.string'
end

name1 = Name.new(first: 'john', last: 'doe') # => #<Name first="john" last="doe">
name2 = Name.new(name1)                      # => #<Name first="john" last="doe">

name1.equal?(name2) # => false

name1.first.reverse!

name1.first # => "nhoj"
name2.first # => "john"

this way you can still have mutable structs if you want but you still aren't as likely to accidentally mutate the state of another object.

from dry-types.

I might add a separate issue for this, but I think that Dry::Types::Struct objects should also change their behavior such that attribute values are duplicated upon instantiation

We can provide a special struct type that does that if it could be useful. But I wouldn't want this to be THE behavior of every struct, because of performance cost.

from dry-types.

True, we should deeply freeze its members. It's gonna cost a lot in terms of performance though so it should be properly documented.

from dry-types.

Given the performance cost, can you imagine anyone actually wanting to use such a class?

from dry-types.

Of course, there are places where being so paranoid is a good idea, esp when you rely heavily on object's equality and you need to make sure nothing can mutate them. I had this kind of code a couple of times, I always used truly immutable objects there.

from dry-types.

It's gonna cost a lot in terms of performance though so it should be properly documented.

Assuming this is properly documented are you comfortable then with moving forward on this? I'm happy to do a PR at some point I just want to make sure that this is inline with what the project's goals

from dry-types.

Yes let's do this

from dry-types.

On it. I assume you are fine with pulling in IceNine as a dependency for this?

from dry-types.