[Python-ideas] Allow manual creation of DirEntry objects

[Brendan Moloney]

Hi,

I have been using the 'scandir' package (https://github.com/benhoyt/scandir) for a while now to
speed up some directory tree processing code. Since Python 3.5 now includes 'os.scandir' in the
stdlib (https://www.python.org/dev/peps/pep-0471/) I decided to try to make my code work with
the built-in version if available.

The first issue I hit was that the 'DirEntry' class was not actually being exposed
(http://bugs.python.org/issue27038). However in the discussion of that bug I noticed that the
constructor for the 'DirEntry' class was deliberately being left undocumented and that there
was no clear way to manually create a DirEntry object from a path. I brought up my objections
to this decision in the bug tracker and was asked to have the discussion over here on
python-ideas.

I have a bunch of functions that operate on DirEntry objects, typically doing some sort of filtering
to select the paths I actually want to process. The overwhelming majority of the time these functions
are going to be operating on DirEntry objects produced by the scandir function, but there are some
cases where the user will be supplying the path themselves (for example, the root of a directory tree
to process). In my current code base that uses the scandir package I just wrap these paths in a
'GenericDirEntry' object and then pass them through the filter functions the same as any results
coming from the scandir function.

With the decision to not expose any method in the stdlib to manually create a DirEntry object, I am
stuck with no good options.  The least bad option I guess would be to copy the GenericDirEntry code
out of the scandir package into my own code base.  This seems rather silly.  I really don't understand
the rationale for not giving users a way to create these objects themselves, and I haven't actually seen
that explained anywhere. I guess people are unhappy with the overlap between pathlib.Path objects
and DirEntry objects and this is a misguided attempt to prod people into using pathlib. I think a better
approach is to document the differences between DirEntry and pathlib.Path objects and encourage
users to default to using pathlib.Path unless they have good reasons for using DirEntry.

Thanks,
Brendan
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