default option fix

[loadkpi]

fix #19

[JelF]

Save back-compatibility. It is important.

Imagine following scenarios

1. Somebody used writer: false to disable auto-assignment of attribute which should be added in attributes (I.e. he overrided reader)
2. Somebody used reader: false to prevent attribute from exposing into attributes

[JelF]

Incorrect semantic.

1. Save define_reader (at least for back-compatibility)
2. Define private_reader or something
3. i think, attribute :name, reader: :private serves this case best

[JelF]

Private reader should not be exposed. Also you are breaking back-comp here

[frvade]

Private reader should not be exposed

He is actually fixing this. Now only public readers will show up in attributes. But this will actually break backward-compatibility and needs to be discussed.

[loadkpi]

Probably it's better to compare #attributes behavior.
This code has similar results on master branch and on the pull request branch:

Class.new do
  include Tainbox
  attribute :a1
  attribute :a2, reader: false
  attribute :a3, writer: false
end.new.attributes
# => {:a1=>nil, :a3=>nil}

For me it's not really clear why respond_to? was used with the option to include private methods in its result before.
So let me know if I miss something.

[JelF]

sorry, you are correct here

[JelF]

forgot to request changes

[frvade]

1. writer: false removes any opportunity to actually write anything to the attribute. So with this option enabled you must override reader to simulate attribute. Private writer combined with excluding private writers from mass-assignment will solve the problem without having to simulate the attribute behaviour. In any casedefault: setting should work with writer: false.
2. reader: false disables any way to read the attribute. Why anyone would use it? What if I want to read it inside the instance? To make mass-assignment work with a pseudo-attribute which will set other attributes we can just make the reader private. We will have a reader inside an instance and with the proposed changes it will not show up in the attributes.