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Author Jim.Jewett
Recipients Jim.Jewett, berker.peksag, corona10, gvanrossum, serhiy.storchaka, xtreak
Date 2020-07-28.05:56:06
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There are a zillion reasons a filename could be wrong -- but the standard
says to trust the filesystem.  So if it sniffs based on contents, it isn't
quite following the standard.  It is probably still a useful tool, but it
won't be the One Right Way, and it isn't even clear that it should replace
current heuristics.

On Mon, Jul 27, 2020 at 7:22 PM Guido van Rossum <>

> Guido van Rossum <> added the comment:
> Whether the data was retrieved over a network has nothing to do with it.
> There are complementary ways of guessing what data you are working with --
> guess based on the filename extension or sniff based on the contents of the
> file (or downloaded data).
> There are a zillion reasons why the filename could be a lie -- e.g. a user
> could pick the wrong extension, or rename a file, or a tool could save a
> file using the wrong extension or no extension at all. Then again sometimes
> the contents of the file might not be enough, e.g.
> ```
> foo() // bar
> ```
> is both valid Python and valid JavaScript. :-)
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Date User Action Args
2020-07-28 05:56:06Jim.Jewettsetrecipients: + Jim.Jewett, gvanrossum, berker.peksag, serhiy.storchaka, corona10, xtreak
2020-07-28 05:56:06Jim.Jewettlinkissue40841 messages
2020-07-28 05:56:06Jim.Jewettcreate