Add Support for Relative Path Calculation

[gshmu]

Is your feature request related to a problem?

No response

Describe the solution you'd like

Current Behavior

The yarl library provides an intuitive API for handling URL parsing and construction. However, it lacks an operator for directly calculating the relative path between two URLs.

Proposed Feature

Introduce support for using the subtraction operator (-) to calculate the relative path between two URL objects. This would simplify the syntax for relative path calculation, making it more intuitive. The operator could calculate the difference between two URLs' paths and return the relative path.

Example Usage

from yarl import URL

url1 = URL('http://example.com/docs/')
url2 = URL('http://example.com/docs/a.json')

relative_path = url1 - url2  # Proposed feature

print(relative_path)  # Expected output: 'a.json'

Describe alternatives you've considered

This feature would simplify URL handling in situations where relative paths are frequently needed and would make yarl even more developer-friendly. It would be especially useful in web applications and API development.

Thank you for considering this feature request!

Additional context

No response

Code of Conduct

• I agree to follow the aio-libs Code of Conduct

[gshmu]

eg: https://github.com/fastapi/fastapi/pull/12421/files

[babieiev]

This idea looks quite interesting. But I think it would be more intuitive if we "subtracted" the shorter link from the longer one.
Like this:

from yarl import URL

target = URL('http://example.com/docs/a.json')
base = URL('http://example.com/docs/')

relative_path = target - base

print(relative_path)  # Expected output: 'a.json'

So I would just swap the operands.

[babieiev]

I haven't contributed to this repository yet, but it looks like a "good first issue" to me. I'll try to implement your idea today or tomorrow.

[bdraco]

We discovered that approach in #1340 isn't ready to ship so I've opened #1391 to revert it so we can try again.

more details starting at #1388 (comment)