[Python-Dev] Re: os.path.commonprefix breakage (original) (raw)

Tim Peters tim_one@email.msn.com
Thu, 17 Aug 2000 19:29:16 -0400

[Skip, as quoted by MarkH]

I don't realize that because a bug wasn't noticed for a long time was any reason not to fix it. Guido was also involved in the repair of the bug, and

[MarkH]

I think most people agreed that the new semantics were preferable to the old. I believe Tim was just having a dig at the fact the documentation was not changed, and also wearing his grumpy-conservative hat (well, it is election fever in the US!)

Not at all, I meant it. When the code and the docs have matched for more than 6 years, there is no bug by any rational definition of the term, and you can be certain that changing the library semantics then will break existing code. Presuming to change it anyway is developer arrogance of the worst kind, no matter how many developers cheer it on. The docs are a contract, and if they were telling the truth, we have a responsibility to stand by them -- and whether we like it or not (granted, I am overly sensitive to contractual matters these days <0.3 wink>).

The principled solution is to put the new functionality in a new function. Then nobody's code breaks, no user feels abused, and everyone gets what they want. If you despise what the old function did, that's fine too, deprecate it -- but don't screw people who were using it happily for what it was documented to do.

But remember - the original question was if the new semantics should return the trailing "\" as part of the common prefix, due to the demonstrated fact that at least some code out there depends on it.

Tim wanted a bug filed, but a few other people have chimed in saying nothing needs fixing. So what is it? Do I file the bug as Tim requested? Maybe I should just do it, and assign the bug to Guido - at least that way he can make a quick decision?

By my count, Unix and Windows people have each voted for both answers, and the Mac contingent is silently laughing .

hell-stick-in-fifty-new-functions-if-that's-what-it-takes-but-leave- the-old-one-alone-ly y'rs - tim