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

[Koos Zevenhoven]

On Sat, Mar 26, 2016 at 9:10 PM, Brett Cannon <brett at python.org> wrote:

>
>
> On Fri, 25 Mar 2016 at 16:50 Greg Ewing <greg.ewing at canterbury.ac.nz>
> wrote:
>
>> >>>On 24.03.2016 22:06, Koos Zevenhoven wrote:
>> >>>
>> >>>Or even better, that you could do p"filename.txt", which would give
>> you a
>> >>>Path string object.
>>
>> That would tie Path objects deeply into the parser and compiler,
>> which I'm not sure is a good idea.
>>
>
> I'll go one step further than Greg and say that it's not a good idea. To
> make something like this work you have two options. One is you do what
> importlib does and very carefully construct it to only rely on built-in
> modules (and if you look at
> https://hg.python.org/cpython/file/default/Lib/pathlib.py you will notice
> that is no where near true ATM). Two, is Python gets a two-tier syntax
> system for before and after pathlib is imported and available. That would
>  mean that all the dependencies of pathlib would need to not use this
> syntax until it's bootstrapped in. If you notice, both solutions are
> extremely painful to implement and radiate well past the code in pathilb.py
> and would potentially become hard to maintain.
>

As I understand it, this could be implemented by making the compiler
essentially turn p"/path/to/whatever" into something like
_make_path("/path/to/whatever"), where _make_path would be builtin and do
something like this.

def _make_path(str_path):
    import pathlib
    return pathlib.Path(str_path)

Unless of course Path could be modified to import its dependencies on
demand and put in builtins. Am I missing something crucial?


>
> I also want to mention two things. One, pathlib.path is a thing now and
> something most people are probably not aware of as an alternative to doing
> `str(path)`:
> https://docs.python.org/3/library/pathlib.html#pathlib.PurePath.path .
>

I assume you meant to type pathlib.Path.path, so that Path("...").path ==
str(Path("...")). That's a good start, and I'm looking forward to Serhiy's
patch for making the stdlib accept Paths. But if Path will not subclass
str, we also need new stdlib functions that *return* Paths.

 - Koos
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