jsonargparse

jsonargparse copied to clipboard

🐛 Bug report

No way of selecting a subtype from a union type.

When adding an argument which is a union of two types there seems to be no direct way of specifying the desired type to be parsed/instantiated. This seems to be automatically detected from the argument names and values which is undesirable in scenarios where subtypes have similar arguments but different behaviors when instantiated.

To reproduce

from dataclasses import dataclass
from jsonargparse import ArgumentParser

@dataclass
class A:
    foo: int

@dataclass
class B:
    foo: int
    bar: float = 1.0


if __name__ == "__main__":
    parser = ArgumentParser(description="Example CLI", exit_on_error=False)
    parser.add_argument("--cfg", type=A | B)
    args = parser.parse_args(["--cfg.foo=1"])
    print(args)
    print(parser.instantiate_classes(args))

Expected behavior

A way of selecting the desired subtype from the command line.

Environment

• jsonargparse version: 4.33.1
• Python version: 3.10
• How jsonargparse was installed: pip
• OS: MacOS