New submission from Barney Gale <barney.g...@gmail.com>:
`pathlib.Path._init()` accepts a 'template' argument that pathlib uses - in some cases - to preserve the current accessor object when creating modified path objects. This works for `resolve()`, `absolute()` and `readlink()`, *but no other cases*! As customizing the accessor is not something we support (yet! see https://discuss.python.org/t/make-pathlib-extensible/3428), and the majority of path methods do not call `_init()` with a 'template' argument (and so do not preserve the accessor), I suggest this internal functionality be removed. Together with bpo-39682 / gh-18846, I believe this would allow us to remove `Path._init()` entirely, which would be a small performance win and a simplification of the code. Demo: ``` import pathlib class CustomAccessor(pathlib._NormalAccessor): pass def print_accessor(path): if isinstance(path._accessor, CustomAccessor): print(" %r: custom" % path) else: print(" %r: normal" % path) print("Here's a path with a custom accessor:") p = pathlib.Path("/tmp") p._accessor = CustomAccessor() print_accessor(p) print("Our accessor type is retained in resolve(), absolute() and readlink():") print_accessor(p.absolute()) print_accessor(p.resolve()) #print_accessor(p.readlink()) print("But not in any other path-creating methods!") print_accessor(p.with_name("foo")) print_accessor(p.with_suffix(".foo")) print_accessor(p.relative_to("/")) print_accessor(p / "foo") print_accessor(p.joinpath("foo")) print_accessor(p.parent) print_accessor(p.parents[0]) print_accessor(list(p.iterdir())[0]) print_accessor(list(p.glob("*"))[0]) print_accessor(list(p.rglob("*"))[0]) #print_accessor(p.expanduser()) ``` ---------- components: Library (Lib) messages: 364783 nosy: barneygale priority: normal severity: normal status: open title: pathlib: remove partial support for preserving accessor when modifying a path type: performance versions: Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue40038> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
