[feature] add self.*_path properties that return pathlib.Path

[mattyclarkson]

• I've read the CONTRIBUTING guide.

We have recipe_folder, source_folder, etc that return Optional[str].

It would be nice to work with filesystem paths using pathlib.Path.

As the *_folder can be None in certain stages, it is usually a programming error accessing them when they are None.

It would be nice to have the following accessors on the ConanFile:

    @property
    def package_path(self) -> Path:
        """
        :returns: The location of the final packaging location              
        """
        assert self.package_folder is not None, "`package_folder` is `None`"
        return Path(self.package_folder)

Then we can use it like so:

    def build(self) -> None:
        exe = self.package_path / "bin" / "hello-world"
        exe.parent.mkdir()
        with exe.open(encoding="utf8") as stream:
            stream.write("#! /bin/sh\necho 'Hello, world!'')
        exe.chmod(0o755)

Which is much nicer that the equivalent code with os.path.

[memsharded]

The problem with this is that Conan 1.X still supports Python 2.7 (sigh, I know...), so this couldn't be added.
Then we need to keep the current xxx_folder as strings for the Conan 1.X -> Conan 2.0 migration.

We will probably start to use Pathlib gradually at Conan 2.X (once the migration cliff has been surpassed), and from there we might be able to consider this request.

[mattyclarkson]

Makes sense.

A possible way to support this AOT would be to add pathlib2 in conans/requirements.txt:

pathlib2>=2;python_version<='2.7'

try:
    from pathlib import Path
except ImportError:
    from pathlib2 import Path

Then we could have the newer properties available before v2.0.0 to aid transition. It might be possible then to just nuke *_folder attributes as a backwards incompatible change. Would be nice to be in pathlib world in v2.

[SSE4]

The problem with this is that Conan 1.X still supports Python 2.7 (sigh, I know...), so this couldn't be added. Then we need to keep the current xxx_folder as strings for the Conan 1.X -> Conan 2.0 migration.

does it? it seems to be removed already #11357 #11360

[ytimenkov]

@memsharded Are there any chances that Conan 2.0 will have it? I find it extremely convenient to be able to write self.source_folder / "build".

I think it is important to make this switch in Conan 2.0 so new recipes can rely on this functionality.

[memsharded]

Maybe now that Conan 1.X dropped Py2 support, it is an option. Someone wants to contribute a PR for Conan 1? (it needs to be there, in order to have compatible recipes in both 1.X and 2.0)

[SSE4]

here we go: #11585