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Instantiating sub-class from super


On 10/17/19, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> On Wed, 16 Oct 2019 19:52:50 +0100, MRAB <python at mrabarnett.plus.com>
> declaimed the following:
>
>>Researchers find bug in Python script may have affected hundreds of
>> studies
>>https://arstechnica.com/information-technology/2019/10/chemists-discover-cross-platform-python-scripts-not-so-cross-platform/
>
> 	That article bugs me...
>
> 	As I understand it, the results are affected by the ORDER in which,
> otherwise independent, file NAMES were returned by the OS.
>
> 	Fine: manually ordering the names by some algorithm produces consistent
> results across various OSs -- but what evidence is there that this file
> name sort is producing "correct" results? What is the sorting criteria --
> it is not mentioned in the article. Are the file names time-stamped (in
> which case a time-ordered sort does make sense)?

I'm bugged by how the article mis-characterizes the fundamental
problem. The operating system has nothing to do with the order of a
directory listing, which varies even with an OS, depending on the file
system. The latter could store each entry in a tree structure that's
sorted by filename, or it could use a mapping with hash values, or it
could simply use the first available slot in a list, based on the
order of past create and delete operations.