class-level instance variables

[skippy]

hey folks,

I'm looking at using the base protobuf class and wrapping business logic around it in a separate class, using class inheritance. However, this doesn't work in this library:

require 'protobuf'
require 'protobuf/message'
module Corp
  module Protobuf
    class Error < ::Protobuf::Message
      required :string, :foo, 1
    end
  end
end
module Corp
  class ErrorHandler < Corp::Protobuf::Error
  end
end
# this works
Corp::Protobuf::Error.new(foo: :bar).encode #=> "\n\x03bar"
#this does not
Corp::ErrorHandler.new(foo: :bar).encode #=> ""

The root issue is within lib/protobuf/message/fields.rb and the fact that there is a somewhat hidden class instance variable @field_store and a bunch of class instance variables uses for memoization. The module doesn't define it as a class instance variable, obviously, but it extends the message class, which makes it a class instance variable.

Is this intended behavior? Do you think it is worth fixing? If so, and since active_support is already included, I think mattr_accessor will do the trick (I can submit a patch and find out :) And of course I can change my class to use the protobuf as an internal object and forgo inheritance all together.

thoughts? And thank you for the library!

[localshred]

@skippy definitely not intended. I extracted a bunch of class-level methods from Message about a year ago and obviously didn't have a test for what you're doing. Would love to see a PR fixing it. 👍

[localshred]

Fixed under v3.4.4.

[skippy]

thanks!