📝 Fix policy test and doc

2026-07-28 02:42:21 +00:00 · 2026-07-07 10:28:16 +08:00
parent d3bff1305d
commit 3bac025acf
20 changed files with 844 additions and 60 deletions
@@ -0,0 +1,79 @@
+---
+name: runtime-sink-file-default-policy-or-none
+group: api
+category: runtime
+update-time: 20260707
+description: Read the default runtime file policy from a RuntimeSink only when it is actually file-backed.
+key-word:
+    - runtime
+    - sink
+    - file
+    - truthful
+---
+
+## Runtime-sink-file-default-policy-or-none
+
+Read the default runtime file policy from a `RuntimeSink` only when it is actually file-backed.
+
+This is the truthful companion to `file_default_policy()`. Prefer it when default-policy inspection should not fabricate a fallback object on non-file sinks.
+
+### Interface
+
+```moonbit
+pub fn RuntimeSink::file_default_policy_or_none(self : RuntimeSink) -> FileSinkPolicy? {
+```
+
+#### input
+
+- `self : RuntimeSink` - Runtime sink whose default 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(default_policy)`.
+- `QueuedFile` runtime variants forward the wrapped inner file sink default policy as `Some(default_policy)`.
+- Non-file runtime variants return `None`.
+- This helper is useful when callers need to compare runtime drift or restore defaults without fabricating file semantics.
+
+### How to Use
+
+Here are some specific examples provided.
+
+#### When Need Truthful Baseline Policy Visibility
+
+When tooling should inspect defaults only for real file-backed sinks:
+```moonbit
+let defaults = sink.file_default_policy_or_none()
+```
+
+In this example, `None` means the runtime sink has no file default policy.
+
+#### When Compare Current And Default Policy Truthfully
+
+When diagnostics should avoid fallback policy objects:
+```moonbit
+match (sink.file_policy_or_none(), sink.file_default_policy_or_none()) {
+  (Some(current), Some(defaults)) => ignore((current, defaults))
+  _ => ()
+}
+```
+
+In this example, comparisons happen only when real file semantics exist.
+
+### Error Case
+
+e.g.:
+- If the runtime sink is not file-backed, the method returns `None`.
+
+- If callers only need a drift boolean, `file_policy_matches_default()` remains simpler.
+
+### Notes
+
+1. Prefer this helper over `file_default_policy()` for truthful runtime diagnostics.
+
+2. `file_default_policy()` remains available as the compatibility fallback API.