Rails - Jan 2007 - AR clone interaction with initialization logic in model

All,

Assume an AR model with an after_initialize method, which is used to
initialize attribute values.  An example would be:

class X < ActiveRecord::Base
...

  def after_initialize
    self.attr1 = 0
  end
end

Further assume that x is an instance of X, and x.attr1 has been assigned
the value 3.

If I do y = x.clone, and interrogate the value of y.attr1, I''ll get 0.
This makes sense given the source code for AR#clone.  But I expected the
value of attr1 to be 3, not 0.

I would think that clone should completely instantiate the new object,
and _then_ assign the attribute values from the original object.

Is the current behavior a bug, or am I missing some important
philosophical point.

Thanks,
Wes

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One way around this is to modify the after_initialize logic to not 
assume that the attribute values should always be set, like so:

class X < ActiveRecord::Base
...

  def after_initialize
    if self.new_record?
      self.attr1 ||= 0
    end
  end
end

In a clone situation, attr1 will already have a value and therefore, 
won''t be initialized to a default value.

Still, I feel like clone has a bug in it.  Here''s what happens in a 
regular Ruby object:

class X
  attr_accessor :val

  def initialize
    @val = 5
  end
end

x = X.new
x.val
=> 5
x.val = 23
=> 23
y = x.clone
=> #<X:0x2c33148 @val=23>

The value of @val in the cloned object is 23, not 5.

While I concede that after_initialize is a standalone method that 
officially has nothing to do with Ruby object initialization, I still 
feel like the clone method should set the attribute values after the 
object is instantiated.

Wes

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