YAML

YAML... Yet another markup language. YAML Ain't a Markup Language!

Explicit Mappings

Mappings in YAML can be defiend either as implicit, such as:

YAML

foo: bar
one: two

Or using the explicit notation:

YAML

?foo
: bar
?one
: two

Why ever use the explicit notation? Well, you can use any kind of yaml structure as the key:

YAML

%YAML 1.2
---
? - Detroit Tigers
  - Chicago cubs
: - 2001-07-23

>>> from ruamel.yaml import YAML
>>> yaml=YAML()
>>> yaml.load("""%YAML 1.2
... ---
... ? - Detroit Tigers
...   - Chicago cubs
... : - 2001-07-23""")
{('Detroit Tigers', 'Chicago cubs'): [datetime.date(2001, 7, 23)]}

Note that this requires a parser capable of loading YAML 1.2. As of 2023-12-20, the more popular yaml and PyYaml packages don't support this syntax.