On 1/4/2011 6:39 PM, Guido van Rossum wrote:
So, that significantly weakens the argument that this optimization will break unit tests, since I am happy to promise never to optimize these builtins, and any other builtins intended for I/O.
This is one comprehensible rule rather than a list of exceptions, so easier to remember. It has two rationales: such often need to be over-riden for testing, possibly in hidden ways; such are inherently 'slow' so optimizing dict lookup away hardly makes sense.
-- Terry Jan Reedy