Nested hash field defined by external class doesn't work

[akoltun]

Model = Struct.new(:content)

class Nested < Disposable::Twin
  property :nested_property
end

class Outer < Disposable::Twin
  include Property::Hash
  property :content, field: hash, twin: Nested 
end

Outer.new(Model.new({nested_property: 1}))  # will fail with message: 
# NoMethodError: undefined method `nested_property' for {:nested_property=>1}}:Hash

The reason of failing is that the Property::Hash module includes the following three modules (NestedDefaults, Property::Struct, Hash::Sync) in the nested class by means of the feature mechanism which works only for nested fields defined in the block but not in the separate class.

Since this feature behaviour seems to be correct (in general modules should be explicitly included in the classes) I can see two possible ways to solve an issue:

• use another dedicated way to include these specific modules into the nested class (in this particular case I see it to be appropriated)
• explicitly include these modules in the nested class. For now it is just a workaround which uses undocumented functions. In order to become a solution it should be documented and preserved from the unannounced changes but actually it looks ugly:

class Nested < Disposable::Twin
  feature Disposable::Twin::Property::Hash::NestedDefaults
  feature Disposable::Twin::Property::Struct
  feature Disposable::Twin::Property::Hash::Sync

  property :nested_property
end

It's nicer to have just one module that should be included and which will do this work. Something like this:

class Nested < Disposable::Twin
  feature Disposable::Twin::Property::Hashable

  property :nested_property
end

[apotonick]

What happens if you do

class Nested < Disposable::Twin
  include Property::Hash
  property :nested_property
end

[akoltun]

The same exception:
NoMethodError: undefined methodnested_property' for {:nested_property=>1}}:Hash`

Because Property::Hash itself does not provide methods to deserialise hash into object. But uses feature mechanism to mix-in necessary modules into nested properties. But feature mechanism does work only for nested blocks.