[Python-Dev] Tuples and underorderable types (original) (raw)

Raymond Hettinger python at rcn.com
Fri Apr 24 20:19:39 CEST 2009

Would it make sense to provide a default ordering whenever the types are the same? This doesn't work when they are not the same :-)

_ ~ @ @ _/

Instead, you could make the decorating a bit more sophisticated:

decorated = [(key, id(value), value) for key, value in blah(values)] or even: decorated = [(key, n, value) for n, key, value in enumerate(blah(values))]

I already do something along those lines in heapq.nsmallest() and nlargest() to preserve sort stability. The real issue isn't how to fix one particular module. The problem is that a basic python pattern is now broken in a way that may not readily surface during testing.

I'm wondering if there is something we can do to mitigate the issue in a general way. It bites that the venerable technique of tuple sorting has lost some of its mojo. This may be an unintended consequence of eliminating default comparisons.

Raymond

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