python / python/mypy

Use mypy to find backward incompatibilities between library versions

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feature
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Python
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Description

Feature

Would it be possible to use mypy to find backward incompatibilities between versions of a library?
I'm thinking about snapshotting the signature of all modules/functions/classes at some point, and checking whether for a later version, the API is a superset/subtype (According to Liskov, probably.)

Pitch

Feel free to close if this doesn't belong here. But I've the impression that Mypy has the logic to figure out whether one function or class is a subtype of another, so I wonder whether that would be possible for a package as a whole. This would be a big help to discover breaking changes in a library.

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Research direction

The issue names no files, tests, or entry points. Start by examining mypy's existing subtype-checking and API analysis capabilities, then determine how library signatures could be captured and compared across versions. Done would require a defined, implementable approach for detecting backward-incompatible changes.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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