Default values can't look like {{something}}

[dconathan]

🐛 Bug report

Default values can't look like {{something}}

To reproduce

import jsonargparse

# Here define one or more functions or classes
def func1(param1: str="{{something}}"):
    ...

# Run the CLI providing the components
jsonargparse.CLI([func1], error_handler=None)

Invoking this fails with a long traceback that looks like something related to encoding the default value as yaml?

    raise ConstructorError("while constructing a mapping", node.start_mark,
yaml.constructor.ConstructorError: while constructing a mapping
  in "<unicode string>", line 1, column 1
found unhashable key
  in "<unicode string>", line 1, column 2

My guess is because if this is a value in yaml it looks like you're trying to build a dict with a dict as a key. Is there a workaround for this? My use case is I want to pass in jinja template-like things.

Expected behavior

The CLI would run without error.

Environment

• jsonargparse version (e.g., 4.8.0): 4.16.0
• Python version (e.g., 3.9): 3.10
• How jsonargparse was installed (e.g. pip install jsonargparse[all]): pip install jsonargparse
• OS (e.g., Linux): MacOS

[mauvilsa]

Thank you for reporting! I just pushed a fix for this in commit 72672b4.

[dconathan]

Thanks!