[Python-Dev] The desired behaviour for resolve() when the path doesn't exist (original) (raw)

Serhiy Storchaka storchaka at gmail.com
Tue Jan 7 16:26:20 CET 2014

06.01.14 12:38, Vajrasky Kok написав(ла):

This is related with ticket 19717: "resolve() fails when the path doesn't exist".

Assuming /home/cutecat exists but not /home/cutecat/aa, what is the desired output of Path('/home/cutecat/aa/bb/cc').resolve(strict=False)? Should it be: "/home/cutecat" (the existed path only), "/home/cutecat/aa" (the first non-existed path; my current strategy), or "/home/cutecat/aa/bb/cc" (the default behaviour of os.path.realpath)?

The readlink command has three canonicalize modes

-f' --canonicalize' Activate canonicalize mode. If any component of the file name except the last one is missing or unavailable, `readlink' produces no output and exits with a nonzero exit code. A trailing slash is ignored.

-e' --canonicalize-existing' Activate canonicalize mode. If any component is missing or unavailable, `readlink' produces no output and exits with a nonzero exit code. A trailing slash requires that the name resolve to a directory.

-m' --canonicalize-missing' Activate canonicalize mode. If any component is missing or unavailable, `readlink' treats it as a directory.

Behavior of os.path.realpath() is equivalent to --canonicalize-missing. Current behavior of pathlib.Path.resolve() is equivalent to --canonicalize-existing.

Behavior of --canonicalize-existing can be derived from --canonicalize, just check that resulting patch exists. But other modes can't be derived from --canonicalize-existing.

def resolve_existing(path): path = path.resolve() if not path.exists(): raise FileNotFoundError(errno.ENOENT, 'No such file or directory: %r' % str(path)) return path

So perhaps two main modes should be --canonicalize (default) and --canonicalize-missing (with missing=True)?

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