Skip to content

pleroma

πλήρωμα — Greek; Sum total.

pleroma provides base classes that add a composable merge operation to dataclasses and pydantic v2 models.

What it does

Given a collection of instances of the same type, merge folds them into a single instance using a last non-None wins strategy by default. Both the traversal order and the field-level resolution can be overridden per subclass.

import dataclasses
from pleroma import MergeableMixin

@dataclasses.dataclass
class Config(MergeableMixin):
    host: str | None = None
    port: int | None = None
    debug: bool | None = None

defaults = Config(host="localhost", port=8080, debug=False)
overrides = Config(port=9090)

Config.merge([defaults, overrides])
# Config(host='localhost', port=9090, debug=False)

Features

  • MergeableMixin — drop-in mixin for any @dataclass
  • MergeableModel — frozen pydantic v2 base class with the same interface
  • Predefined iteration strategies — iter_all, iter_reversed, iter_first, iter_last
  • Customisable traversal via _iter_instances
  • Customisable field resolution via _merge_two
  • Fully typed (PEP 561, py.typed marker)