feat: ✨ Allow for functools.partial and functions returning an awaitable as autocomplete

[Paillat-dev]

Summary

Allows usage of functions with any number of optional parameters as autocomplete. This allows by extent the usage of partials and similar as autocomplete.

Fixes #2668
Superseeds #2669

Information

• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed).
• This PR is not a code change (e.g. documentation, README, typehinting,
  examples, ...).

Checklist

• I have searched the open pull requests for duplicates.
• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• If type: ignore comments were used, a comment is also left explaining why.
• I have updated the changelog to include these changes.

[pycord-app]

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This pull request can be checked-out with:

git fetch origin pull/2914/head:pr-2914
git checkout pr-2914

This pull request can be installed with:

pip install git+https://github.com/Pycord-Development/pycord@refs/pull/2914/head

[Paillat-dev]

Ok this is kind of spaghetti code, but I mean it works... In next autocompletes should probably be made into classes and it should make most of this mess clearer

[Copilot]

Pull Request Overview

This PR adds support for using functools.partial and functions returning awaitables as autocomplete handlers for Discord application commands. The key enhancement is making the autocomplete system more flexible by allowing functions with optional parameters and improving the detection of async behavior.

• Enhanced autocomplete function signature detection to support functions with optional parameters
• Improved async handling by checking for awaitable results instead of just coroutine functions
• Added example demonstrating the use of functools.partial for autocomplete

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
examples/app_commands/slash_autocomplete.py	Added example demonstrating functools.partial usage with autocomplete
discord/commands/options.py	Enhanced type annotations and added property-based autocomplete with signature analysis
discord/commands/core.py	Updated autocomplete invocation to use pre-computed method detection and improved async handling
CHANGELOG.md	Added changelog entry documenting the new functionality

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[Paillat-dev]

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