Hacktoberfest 2026: the issues maintainers tagged for October, open and beginner-friendly. Browse Hacktoberfest issues

Support `Any` as an alias for `object` to describe a default typeclass implementation

Open
#307 0 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
38/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
python
Domain
tooling

Research direction

The issue does not name implementation files or tests. Start by locating the handling behind @render.instance(object) and the existing typeclass instance tests, then trace how the object default is recognized. Done means @render.instance(Any) behaves equivalently to @render.instance(object) while the example dispatches the fallback implementation.

Written by the indexing model from the issue text.

Description

Context. In order to define a default implementation (the one used if no other implementation matches), we currently have to write something like this:

from classes import typeclass

@typeclass
def render(data_value) -> str:
    """Render a data value nicely."""

@render.instance(int)
def _render_int(data_value: int) -> str:
    return f'This is an integer: {data_value}'


@render.instance(object)
def _render_int(data_value: object) -> str:
    return f'No idea what this is: {data_value}'


assert render('BADOOM') == 'No idea what this is: BADOOM'

(this script should be runnable as-is.)

Decision. Support Any as a special case to replace object:

@render.instance(Any)
def _render_int(data_value: Any) -> str:    # type: ignore
    return f'No idea what this is: {data_value}'

Consequences.

  • Pro: The code will look a little bit more straightforward;
  • Contra: mypy with common settings might be unhappy about Any being used, but that can be silenced with type: ignore I suppose.
Dominant language
Python
Stars
730
Forks
30
No merged PRs in 30d

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from dry-python/classes

All issues in dry-python/classes

Similar issues

More Python issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.