[Python-Dev] Pathlib enhancements - acceptable inputs and outputs for __fspath__ and os.fspath()

Nick Coghlan ncoghlan at gmail.com
Thu Apr 21 09:29:47 EDT 2016

On 20 April 2016 at 13:16, Stephen J. Turnbull <stephen at xemacs.org> wrote:

> It's people who live in monolingual mono-encoding environments who
> will be using bytes successfully, and be resistent to costly changes
> that don't make their lives better.  But the bytes vs. text cost is
> inherent in using pathlib, so polymorphism doesn't help promote
> pathlib.  It might help promote use of os.scandir in bytes-oriented
> code, though I don't see that as a huge effect nor more than mildly
> desirable.  Is it?

Some of us are also interested in optimised network service development use
cases where UTF-8 already rules the world [1]. It's a vastly different
domain from desktop computing, and different even from traditional stateful
servers where the same instance may be kept running for years.

When "absolutely everything is UTF-8, and your system boundaries are
policed accordingly" is a valid assumption, then writing bytes level
network code is a far more viable option than when you're writing software
to give to other people to run in arbitrary environments (that's how Go is
able to get away with its "all system boundaries use UTF-8" approach - if
you're not prepared to meet that precondition, you don't choose to use Go
in the first place).

I think this is also why we're talking past each other - as a default, I
completely agree it makes sense to present a "str-only" API (that's where
my proposed fspath/_raw_fspath split came from). However, there really are
contexts where "our text is always stored as bytes, those bytes are always
UTF-8 encoded, and our software only needs to work on *nix systems" is a
reasonable approach, and those are the domains where being *able* to stay
entirely in the binary domain is actually a desirable characteristic,
rather than merely a tool for migrating from Python 2.


[1] http://utf8everywhere.org/

Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
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