Switch from ruamel.yaml¶

For code that loads, edits, and saves YAML, start with the import:

-from ruamel.yaml import YAML
+from yamluna import YAML

Remove typ= from the constructor:

-yaml = YAML(typ='rt')
+yaml = YAML()

A complete example¶

from yamluna import YAML

yaml = YAML()
config = yaml.load('replicas: 3  # production\n')
config['replicas'] = 5
print(yaml.dump(config), end='')

Output:

replicas: 5  # production

load(), dump(), comment methods, and the main container and scalar types keep familiar names. Import types such as CommentedMap and LiteralScalarString directly from yamluna. Exceptions also come from yamluna.

Check these differences¶

Your existing code	Change for yamluna
`YAML(typ='rt')`	Use `YAML()`; there is no `typ` argument
`yaml.dump(data, stream)`	Still works; omit `stream` to get a string back
`next(yaml.load_all(text))`	Use `iter()` first, or index the returned list
`indent(...)` to preserve loaded indentation	Remove it; existing layout is kept automatically
New quoted-string objects	Set `yaml.preserve_quotes = True`
Register on one instance, load on another	Register on both or pass a shared `TagRegistry`
`allow_duplicate_keys = True`	Expect a warning and the last value, rather than the first
`yaml.version = (1, 1)` before loading	Input needs a `%YAML 1.1` directive; `version` controls output
Manual repairs to `.ca` comment metadata	Review them; comment ownership differs

Keep indent() for generating new documents in your chosen style. Applying it to existing lists can alter their layout; see limitations.

Custom classes¶

register_class() and to_yaml / from_yaml hooks are supported. Registrations are per instance, and output gains %TAG directives to distinguish class sources. Check that other consumers of your YAML accept those directives.

Custom classes covers registration and hooks.

APIs to replace¶

ruamel.yaml API	Approach
Module-level `load()` / `dump()`	Use a `YAML()` instance
`add_constructor()` / `add_representer()`	Use `register_class()` with hooks
`YAMLObject`	Register the class explicitly or use `@yaml.register`
`HexCapsInt`	Use `HexInt(value, caps=True)`
`DecimalInt`	Use `int` or `ScalarInt`

yamluna focuses on round-trip editing. Other loader modes, arbitrary Python object tags, replaceable parser components, and low-level scan() / compose() / serialize() APIs are outside its API. Keep an existing loader for code that depends on those features.

Verify the switch¶

Run your tests against representative files and review the saved YAML. Tests that expect ruamel.yaml's formatting may need new expected output; check the intended result before updating them. Pay particular attention to custom tags, comments around moved entries, and known limitations.

Behavior differences gives a short summary of output changes.