[Python-Dev] optimizing non-local object access

Skip Montanaro skip@pobox.com (Skip Montanaro)
Thu, 9 Aug 2001 15:15:24 -0500

    Jeff> The real gain comes when you can hoist the type test out of the
    Jeff> loop (though that means proving the type condition is an invariant
    Jeff> of the loop!)

Even more difficult if the programmer can subclass ints, yes?.  Today, if I
see x=x/2 and I know x is an int, I can assume x/2 is also (or a float once
integer division returns floats).  Once ints can be subclassed, a devious
programmer could return something other than an int (say, a float, a
rational, or the string "x/2").