[Python-ideas] Small enhancement to os.path.splitext

[Paul Moore]

Sorry, should have gone to the list.

On 23 April 2010 01:53, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
> I still don't think you can decide based on the file
> system behaviour. What if the user creates his files on
> a case-insensitive system and then copies them to a
> case-sensitive one or vice versa? The intended meaning
> of the extensions doesn't suddenly change when that
> happens.

I don't know if you actually use case insensitive filenames regularly
(an odd question that, in "normal life" I'd immediately assume 99.99%
of people I meet use Windows, but on this list, I tend to assume most
people use Unix/Linux or Mac - sorry if my assumption's mistaken) but
personally, as a Windows user, I try to keep filename case the way I
want it, but I'd tend to double check if moving files to a case
sensitive system. But - and this is the key point here for me - the
filenames I *type* at the command line often don't match the case on
the filesystem (because I'm too lazy to hit the shift key when I know
it doesn't matter, for example) and so my expectations very much are
based on filesystem case sensitivity, and what's more, it's what I
type that's unreliable.

As far as I am concerned, any behaviour that relies on filenames
differing only in case being handled differently is wrong on Windows.
(Yes, that includes gcc's behaviour). All programs should work case
insensitively in all cases when dealing with files. Simple.

That's my view as a Windows user. I rationalise it as being based on
the case sensitivity of the filesystem, but I'll admit I have no
experience with using case sensitive filesystems on Windows (for all
practical purposes, they don't exist). I also have limited experience
with Unix, and all my Unix experience is in situations where all the
filesystems are case sensitive. So arguably, my position is Unix ==
case sensitive, Windows = case insensitive, and a simple switch on
sys.platform would work for me. But desktop Linux systems need to deal
with such things as FAT32-formatted USB disks, Samba filesystems, etc.
And I have no good intuition on how they should be handled. So I fall
back on my original rationalisation, that the filesystem behaviour is
what matters.

So to summarise:
 * Case sensitivity behaviour determined by host OS would work for me
 * But it "feels" wrong
 * Case sensitive everywhere is completely wrong (as it ignores
Windows users' expectations)
 * Choosing a default based on filesystem behaviour is logical, but
hard, and there may be no real requirement for it

Also, making the user choose every time (for example, GNU find with
its -name and -iname options) is not a helpful or portable approach
(e.g., I want find . -name *.sql to find all SQL scripts, regardless
of platform).

Cross-platform tools with a strong focus on file and filename
semantics (for example, DVCSs such as Mercurial) have specialist
needs, and probably should always write custom code. But for "quick"
scripts, something in the standard library which made doing the
"right" thing easy would be a huge help.

Paul