Settings

The didactic-settings distribution. See Guides > Settings for the per-source documentation and usage patterns.

from didactic.settings import (
    Settings,
    EnvSource,
    DotEnvSource,
    FileSource,
    CliSource,
)


class App(Settings):
    debug: bool = False
    port: int = 8080

    __sources__ = (
        FileSource(path="config.toml"),
        EnvSource(prefix="APP_"),
    )


cfg = App.load()
cfg.port                       # the resolved value
cfg.__provenance__["port"]     # 'env' / 'file' / 'default' / 'override'

Sources

source	reads from
EnvSource(prefix=, name="env")	environment variables
DotEnvSource(path=, prefix=, name="dotenv")	dotenv file
FileSource(path=, name="file")	JSON / TOML / YAML by suffix
CliSource(args=, name="cli")	argparse Namespace or dict

Each source has a name keyword used in provenance reporting.

Settings.load

Settings.load(**overrides) walks the declared __sources__ in order, then applies any **overrides. The result is a Settings instance with __provenance__ populated.

The final precedence (lowest to highest) is:

1. The declared default on the field.
2. Sources, in the order declared in __sources__.
3. Keyword overrides passed to load(...).

A field that falls through to its declared default has provenance "default". A field set by a keyword override has provenance "override".