Following from this question, I’d like to set a preferred quoting style to be double-quotes, yet allow strings that can be represented as plain (no quotes) to be shown in plain. This is because I’m trying to fit a “house style” even though single quotes are valid yaml and maybe even preferable for some. Here’s a simple test-case:

import sys
from ruamel.yaml import YAML

data = {
    'a': 'non-plain : scalar',
    'b': 'also nontplain',
    'c': 'plain',
    }

def test():
    yaml = YAML()
    yaml.default_flow_style = False
    # yaml.default_style='"'
    yaml.dump(data, sys.stdout)

test()

This outputs (correctly) with variable quoting:

a: 'non-plain : scalar'
b: "also nontplain"
c: plain

Uncomment the default_style line, everything gets double quotes, thus:

"a": "non-plain : scalar"
"b": "also nontplain"
"c": "plain"

I’d like an option to indicate a preferred quote style to be applied only when needed, else plain non-quoted style:

a: "non-plain : scalar"
b: "also nontplain"
c: plain