Merging

Merging

Coyaml merges sources in the order they are added. Later sources override earlier ones. Dictionaries are merged deeply; lists are replaced.

Multiple sources and order

"""Merging multiple sources: later sources override earlier ones; dicts are deep-merged.

Run:
    PYTHONPATH=src uv run python examples/merging/30_multi_source_merge_order.py
"""

from __future__ import annotations

from coyaml import YSettings
from coyaml.sources.yaml import YamlFileSource


def main() -> None:
    cfg = YSettings()
    # Base config
    cfg.add_source(YamlFileSource('tests/config/config.yaml'))
    # Overlay with changes
    cfg.add_source(
        YamlFileSource('tests/config/extra.yaml')
    )  # this is a different shape; used here only to show precedence

    # Resolve templates after all sources are added
    cfg.resolve_templates()

    print('llm =', cfg['llm'])
    print('debug.db.user =', cfg['debug.db.user'])


if __name__ == '__main__':
    main()

Lists semantics

"""List merge semantics: lists are replaced, not merged per item.

Run:
    PYTHONPATH=src uv run python examples/merging/31_lists_and_merge_semantics.py
"""

from __future__ import annotations

from coyaml import YSettings


def main() -> None:
    base = {'features': ['a', 'b']}
    override = {'features': ['c']}

    cfg = YSettings(base)
    cfg2 = YSettings(override)

    # Emulate merge as done by add_source: the latest source replaces the list
    cfg._data.update(cfg2._data)  # for demonstration; add_source would do a deep merge for dicts only

    print('features =', cfg['features'])  # ['c']


if __name__ == '__main__':
    main()