Inheritance Config Example

This example demonstrates configuration inheritance where multiple config files are merged together, with later files overriding earlier ones. Nested dictionaries are deep-merged, preserving keys that aren't explicitly overridden.

This is useful for layered configuration like: - System defaults (/etc/myapp.yaml) - User overrides (~/.config/myapp.yaml) - Project-local overrides (./myapp.yaml)

An example typer app:

simple_app.py

from typing_extensions import Annotated

import typer
from typer_config.decorators import use_multifile_config

app = typer.Typer()


@app.command()
@use_multifile_config(default_files=["base_config.yml", "local_config.yml"])
def main(
    name: str,
    greeting: Annotated[str, typer.Option()],
    suffix: Annotated[str, typer.Option()] = "!",
):
    typer.echo(f"{greeting}, {name}{suffix}")


if __name__ == "__main__":
    app()

With config files representing different layers:

base_config.yml

name: World
greeting: Hello
suffix: "!"

local_config.yml

greeting: Hey

Note that local_config.yml only overrides greeting, while name and suffix are inherited from base_config.yml.

And invoked with python:

Terminal

$ python simple_app.py
Hey, World!

$ python simple_app.py --suffix "!!"
Hey, World!!

$ python simple_app.py Alice
Hey, Alice!

Missing config files are silently skipped, so you can define optional override locations:

@app.command()
@use_multifile_config(default_files=[
    "/etc/myapp/config.yml",      # system defaults (may not exist)
    "~/.config/myapp/config.yml", # user config (may not exist)
    "./config.yml",               # local config (may not exist)
])
def main(...):
    ...