Re: [Python-ideas] Working with Path objects: p-strings?

30 Mar 2016


      On Wed, Mar 30, 2016 at 6:18 PM, Paul Moore p.f.moore@gmail.com wrote:
...
Of course this doesn't address functions that *return* paths (as
strings). There the caller has to wrap the return value in Path(). Or
the function changes to return Path objects, which won't be backward
compatible (whether that matters depends on what the code is).
So, below was a though of how to deal with this: StringPath, which is
both a str and a Path (and/or perhaps PurePath).
On Sun, Mar 27, 2016 at 2:33 AM, Koos Zevenhoven k7hoven@gmail.com wrote:
...
Well, just to reply to myself, here's a slightly crazy idea, which I'll
mention before I realize that it's a bad idea:
What if there was a another class, say StringPath, that inherits from both
str and Path, which wraps another instance of Path, but is also a str. When
you call its Path methods, it would delegate them to the wrapped Path object
so that functions that now return paths as plain str could in future
versions start returning that type?
While I still think it's a crazy idea, I'm not 100% convinced that it
is the wrong thing to do, because there are already many kinds of Path
objects. So a wrote a super hacky implementation of StringPath.
Instances of something like this could be returned from functions that
now return paths in strings.
Here's a little demo with the toy implementation:
>>> p = StringPath("foo/bar/baz")
    >>> p
    StringPath(PosixPath('foo/bar/baz'))
    >>> isinstance(p, pathlib.Path)
    True
    >>> isinstance(p, str)
    True
    >>> str(p)
    'foo/bar/baz'
    >>> p + 'hello'
    'foo/bar/bazhello'
    >>> p / 'hello'
    PosixPath('foo/bar/baz/hello')
    >>> 'hello' / p
    PosixPath('hello/foo/bar/baz')
    >>> p.split('r')
    ['foo/ba', '/baz']
    >>> pathlib.Path(p)
    PosixPath('foo/bar/baz')
So it's a str, but as soon as you do something Path-like with it, it
gives you a Path back. But for anyone who thinks they have a string,
it's a string, except for its repr.
-Koos
P.S. The implementation I used here is actually completely ridiculous,
but if you want to look at it, it's here:
https://gist.github.com/k7hoven/defb7f2eb9ccd9dbd0be0063a475058e