On May 9, 6:42 am, "Alan Isaac" <[EMAIL PROTECTED]> wrote: > Is there > a warning anywhere in the docs? Should > there be?
I do not think additional documentation here would be helpful. One could note that the default hash value is the object id. Somewhere else you could write that the placement of objects in memory is arbitrary and can be affected by a number of factors not explicity under user control. With those notes scattered throughout the documentation, I'm not sure that you would have found them and recognized the implications with respect to your design and with respect to the deletion of pyc files (which is just one factor among many that could cause different placements in memory). Also, the existing docs describe behavior at a more granular level. How the parts interact is typically left to third-party documentation (i.e. the set docs say what the set methods do but do not give advice on when to use them instead of a dict or list). Out of this thread, the more important lesson is that the docs intentionally do not comment on implemation specific details. When the docs do not make specific guarantees and behavior is left undefined, it is not a good practice to make assumptions about invariants that may or may not be true (in your case, you assumed that objects would be located in the same memory locations between runs -- while that sometimes happens to be true, it is certainly not guaranteed behavior as you found out -- moreover, you've made non-guaranteed assumptions about the arbitrary ordering of an unordered collection -- a definite no-no). Raymond Hettinger -- http://mail.python.org/mailman/listinfo/python-list
