Bug #7893: Issues with loading YAML and respond_to_missing?

• Status: Rejected
• Assignee: tenderlovemaking (Aaron Patterson)
• Target version: -
• ruby -v: 1.9.3p385

[injekt (Lee Jarvis)]

This is perhaps not a bug, I could be missing something, but shouldn't the following code work?

require 'yaml'

class Person
  def initialize(name)
    @attributes = { name: name }
  end

  def method_missing(m, *args, &block)
    @attributes.key?(m) ? @attributes[m] : super
  end

  def respond_to_missing?(m, include_private = false)
    @attributes.key?(m) || super
  end
end

dump = YAML.dump Person.new("lee")
load = YAML.load dump

The YAML.dump appears to work as expected, yet when I attempt to load the dump back, I get the following exception:

/Users/lee/bin/rb:15:in `respond_to_missing?': undefined method `key?' for nil:NilClass (NoMethodError)
  from /Users/lee/.rubies/1.9.3-p385/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:291:in `respond_to?'
  from /Users/lee/.rubies/1.9.3-p385/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:291:in `init_with'
  from /Users/lee/.rubies/1.9.3-p385/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:284:in `revive'

However doing the same thing with JSON for example, works fine: https://gist.github.com/injekt/0a4aa3e25f09ae2f8cba

[Hanmac (Hans Mackowiak)]

the problem is in yaml: to_ruby.rb "if o.respond_to?(:init_with)" so eigher you need to define a init_with method or

def respond_to_missing?(m, include_private = false)
(@attributes && @attributes.key?(m)) || super
end

[drbrain (Eric Hodel)]

• Category changed from core to ext
• Status changed from Open to Rejected
• Assignee set to tenderlovemaking (Aaron Patterson)

As Hanmac noted, this exception is possible with Person.allocate.respond_to? which is exactly what Psych does.

Perhaps Psych needs some documentation improvement around dump and load.