SysPropSource

Return all key-value pairs whose keys start with the given prefix (using dot-separated paths).

Look up a single key and return its value with provenance, or None if absent.

Apply a key transformation before lookup. The mapper transforms the requested key before it is passed to the underlying source.

Compose this source with a fallback. Keys are looked up in this source first; if absent, the fallback is consulted. Provenance tracks the actual providing source.

Compose this source with a fallback. This source is consulted first; if it returns None, the fallback is tried.

Prepend a prefix to all key lookups. For example, source.prefix("db").get("host") looks up "db.host" in the underlying source.

A unique identifier for this source, used in provenance tracking.