From: Justin Collins <justincollins@...>
Date: 2009-02-18T05:52:19+09:00
Subject: Re: Marshal.dump fails on extended OpenStruct

Justin Collins wrote:
> synergism wrote:
>> If I subclass OpenStruct and extend the subclass, I cannot
>> Marshal.dump it.  This is apparently because ostruct.rb has its own
>> custom marshal_dump / marshal_load that only cares about what's in
>> @table:
>>
>>   def marshal_dump
>>     @table
>>   end
>>   def marshal_load(x)
>>     @table = x
>>     @table.each_key{|key| new_ostruct_member(key)}
>>   end
>>
>> Is there no way to fix this in ostruct.rb to allow my 'bad' example
>> below to work?
>>
>> require 'pp'
>> require 'ostruct'
>>
>> case ARGV.first
>>     when /bad/i,nil
>>         class C < OpenStruct
>>             def initialize
>>                 super()
>>                 @var=123
>>             end
>>         end
>>     when /good/i
>>         class C
>>             def initialize
>>                 @struct=OpenStruct.new
>>                 @var=123
>>             end
>>
>>             def method_missing method,*args,&block
>>                 @struct.send method,*args,&block
>>             end
>>         end
>> end
>>
>> c=C.new
>> c.a=:a
>> pp c
>> puts 'c.a=%s ' %  c.a
>> puts 'c var=%s' % c.instance_variable_get('@var')
>> x=Marshal.load(Marshal.dump(c))
>>
>> pp x
>> puts 'x.a=%s ' %  x.a
>> puts 'x var=%s' % x.instance_variable_get('@var')
>>
>>   
>
>
Let me try that again:

require 'ostruct'
require 'pp'

class C < OpenStruct

  def initialize *args
    super
   @var = 123
  end  
  def marshal_dump
    [@table, Hash[self.instance_variables.map { |v| [v, 
self.instance_variable_get("#{v}")] }]]
  end  
  def marshal_load x
    @table = x[0]
    @table.each_key{|key| new_ostruct_member(key)}
    x[1].each do |k,v|
      self.instance_variable_set("#{k}", v) unless k.to_sym == :table
    end
  end
end

c=C.new
c.a=:a
pp c
puts 'c.a=%s ' %  c.a
puts 'c var=%s' % c.instance_variable_get('@var')
x=Marshal.load(Marshal.dump(c))

pp x
puts 'x.a=%s ' %  x.a
puts 'x var=%s' % x.instance_variable_get('@var')