Distribution objects from arbitrary paths

[jaraco]

In GitLab by @pradyunsg on Jul 31, 2019, 05:48

I don’t directly see anything in the API to get information about a dist-info in an arbitrary location.

That’s basically required for pip to switch over to using importlib.metadata. pip currently operates by building a package in a temporary directory and gets metadata about the built package from the dist-info directory, using pkg_resources, especially for PEP 517 builds.

[jaraco]

In GitLab by @jaraco on Aug 31, 2019, 14:14

Maybe all you need is to bypass all of the discovery framework and simply construct importlib_metadata.PathDistribution(path_to_dist_info)?

[jaraco]

In GitLab by @jaraco on Aug 31, 2019, 14:27

Aah, it does look like path_to_dist_info needs to be a pathlib.Path or zipfile.Path (or compatible pathlib2.Path/zipp.Path).

[jaraco]

In GitLab by @jaraco on Aug 31, 2019, 14:43

I also notice now that PathDistribution isn't part of the exported names. And Distribution doesn't expose any helper classmethods (except for discovery by sys.metapath helpers).

@warsaw Do you have an opinion here? Should importlib_metadata expose PathDistribution such that tools like pip can construct an instance? Or should they import the name despite it being excluded from __all__ (acknowledging that the interface is less committed)?

[jaraco]

In GitLab by @warsaw on Sep 2, 2019, 16:53

I don't like importing names that aren't explicitly marked as public. I'm not sure I love exposing PathDistribution. As you imply in your question, would it make sense to add a helper class method and not expose PathDistribution?

[jaraco]

In GitLab by @jaraco on Sep 9, 2019, 12:12

I'm struggling with a good helper class method (or function name) for this behavior, in part because Distribution and the global functions are meant to be generic, for all packages regardless of the distribution type. Consider for example this helper:

class Distribution:
    ...
    @staticmethod
    def at(path_to_metadata):
        """Given a ``pathlib.Path`` referencing the metadata,
        construct a PathDistribution.
        """
        return PathDistribution(path_to_metadata)

It really feels like a roundabout way to make PathDistribution method.

On the other hand, it does provide an abstraction around the constructor, so allows the underlying implementation to move/mutate as needed. I'll work on a patch.

[jaraco]

In GitLab by @jaraco on Sep 9, 2019, 12:24

mentioned in commit 14ac77a

[jaraco]

In GitLab by @jaraco on Sep 9, 2019, 12:25

mentioned in commit 9fc88e9

[jaraco]

In GitLab by @jaraco on Sep 10, 2019, 10:42

closed via merge request !90

[jaraco]

In GitLab by @jaraco on Sep 10, 2019, 10:42

mentioned in commit d2357c7