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PORuby's Kernel#instance_variables can't be removed by remove_instance_variable
 

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  1. PORuby's Kernel#instance_variables can't be removed by remove_instance_variable
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    <p>I have the following code. I am passing it a <code>Mongoid::Document</code>.</p> <pre><code>def clean_object(obj) obj.instance_variables.each do |ivar| obj.send(:remove_instance_variable, ivar) unless ivar == :@attributes end end </code></pre> <p>When I run it, I get the error:</p> <p><code>NameError Exception: instance variable @new_record not defined</code></p> <p>But when I run <code>obj.instance_variables</code> I can plainly see it.</p> <p><code>[:@new_record, :@attributes, :@changed_attributes, :@pending_nested, :@pending_relations, :@metadata</code>...</p> <p>What is going on here and how can I remove these instance variables? How can something exist in obj.instance_variables but not exist when I try to remove it?</p> <p>Also, sometimes I can use: <code>obj.remove_instance_variable</code> but other times it complains the method is private and it forces me to use <code>obj.send(:remove_instance_variable</code>...</p> <p>To put this in a bigger context, I need to serialize the <code>Mongoid::Document</code> to memcached and pull them back. I am stripping out the irrelevant bloat (cached document relationships) on the object that isn't needed for serialization.</p>
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    1. USBrennan Cheung
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    1. COWhat version of Ruby? Also, what are you serializing to? There’s almost certainly a better way to do this. You shouldn’t be mutating an object just to serialize it.
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      1. PORuby's Kernel#instance_variables can't be removed by remove_instance_variable
      1. USAndrew Marshall
    2. CONot reproduced, everything seems to work fine https://gist.github.com/4570992 (mongoid 2.0.1, ruby 1.9.3)
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      1. PORuby's Kernel#instance_variables can't be removed by remove_instance_variable
      1. USDaniel Vartanov
    3. CORuby version is 1.9.2-p290. I am serializing to memcache but that's just to put things in context, the real question is why it says there's an instance variable and when I try to remove it, it says it's not there. The reason for mutating it is because it stores a cached copy of all the Mongoid associations. Also, rspec adds mocks which create singleton classes and that causes Marshal.dump to fail. I'm able to decrease memory usage by 1000% by stripping out the useless data first.
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      1. PORuby's Kernel#instance_variables can't be removed by remove_instance_variable
      1. USBrennan Cheung
 

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