On 7/14/2010 7:32 PM, Tim Peters wrote:
[Nick Coghlan]
You're right, I was misremembering how SequenceMatcher works.
Terry's summary of the situation seems correct to me - adding a new
flag to the constructor signature would mean we're taking a silent
failure ("the heuristic makes my code give the wrong answer on 2.7.0")
and making it a noisy failure ("my code needs to be able to turn the
heuristic off to get the right answer, so it will fail noisily on
2.7.0").
Yup - exactly so.
That's a far cry from the True/False mistake.
Which I'm sure refers to introducing True and False builtins in a
bugfix release. That was _almost_ as bad as the sometimes-hated
heuristic I added to SequenceMatcher ;-)
Me, I like "fail noisily on 2.7.0" for this case - practicality beats
purity, especially when so few people and programs are likely to be
affected by the
backwards-incompatible-but-only-for-those-who-need-to-use-it
SequenceMatcher constructor signature change.
Then tomorrow I will work with Eli on a suggested 2.6/3.1 doc patch
and 2.7 code+doc patch.
--
Terry Jan Reedy
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