Runtime-sink-file-policy-or-none

Read the current runtime file policy from a RuntimeSink only when it is actually file-backed.

This is the truthful companion to file_policy(). Prefer it for diagnostics and recovery logic that must avoid fallback policy objects.

Interface

pub fn RuntimeSink::file_policy_or_none(self : RuntimeSink) -> FileSinkPolicy? {

input

• self : RuntimeSink - Runtime sink whose current file policy should be inspected.

output

• FileSinkPolicy? - Some(policy) when the runtime sink is file-backed, otherwise None.

Explanation

Detailed rules explaining key parameters and behaviors

• Plain File runtime variants return Some(current_policy).
• QueuedFile runtime variants forward the wrapped inner file sink policy as Some(current_policy).
• Non-file runtime variants return None.
• This helper is broader than file_append_mode() or file_auto_flush() because it returns the whole policy object without fallback synthesis.

How to Use

Here are some specific examples provided.

When Need Truthful Policy Diagnostics

When diagnostics should inspect file policy only if file semantics exist:

match sink.file_policy_or_none() {
  Some(policy) => ignore(policy)
  None => ()
}

In this example, None means there is no real file policy to inspect.

When Need Compatibility-free Recovery Decisions

When recovery logic should not treat a fallback object as real state:

let maybe_policy = sink.file_policy_or_none()

In this example, callers can distinguish missing file semantics from a live policy snapshot.

Error Case

e.g.:

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

• If callers need default-policy comparison, pair it with file_default_policy_or_none().

Notes

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

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