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Configured-logger-file-path-or-none ​

Read the effective file path from a ConfiguredLogger only when it is actually file-backed.

This is the truthful companion to file_path(). Prefer it for diagnostics, branching, and recovery logic that must distinguish “not file-backed” from compatibility fallbacks.

Interface ​

moonbit
pub fn ConfiguredLogger::file_path_or_none(self : ConfiguredLogger) -> String? {}

input ​

  • self : ConfiguredLogger - Config-driven runtime logger whose file path should be inspected.

output ​

  • String? - Some(path) when the configured sink is file-backed, otherwise None.

Explanation ​

Detailed rules explaining key parameters and behaviors

  • File-backed sinks return Some(path) through the wrapped RuntimeSink.
  • Queued file sinks forward the wrapped inner file sink path as Some(path).
  • Non-file sinks return None.
  • This helper is observation-only and does not mutate logger state.

How to Use ​

Here are some specific examples provided.

When Need Truthful File-backed Detection ​

When code should branch only if file semantics really exist:

moonbit
match logger.file_path_or_none() {
  Some(path) => println(path)
  None => ()
}

In this example, None means the configured logger is not file-backed.

When Need Path Diagnostics Without Fallback Values ​

When support output should avoid compatibility placeholders:

moonbit
let maybe_path = logger.file_path_or_none()

In this example, callers can keep “no file semantics” distinct from a real path.

Error Case ​

e.g.:

  • If the configured sink is not file-backed, the method returns None.

  • If callers need the broader file snapshot or queue context, prefer file_state_or_none() or file_runtime_state().

Notes ​

  1. Prefer this helper over file_path() for truthful runtime diagnostics.

  2. file_path() remains available as the compatibility fallback API.

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