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by prodigal_erik 5251 days ago
Less relevant how? nil.object_id is still 4 in MRI 1.9.2.

The article noted that all integers have odd ids, but not why—the LSB is a http://c2.com/cgi/wiki?TagBit in MRI. I would hope other implementations are permitted to choose different schemes; it would suck if user code began assuming nobody found a use for more than one tag bit.
1 comments
jarin 5251 days ago
This situation was most encountered by Rails developers trying to access the ID of an ActiveRecord object. Since they changed the method to object_id in Ruby 1.9, calling id on a nil object should just give a NoMethodError instead of that slightly cryptic warning.
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prodigal_erik 5249 days ago
Ah, that was a mistake. ActiveRecord should have avoided :id until it was renamed in core Ruby, or returned some sentinel (other than nil) whose :id method fails. Assuming Ruby didn't critically depend on :id succeeding for every object, that is.
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