Computed Var Dependency Tracking Limits

Computed Var Dependency Tracking Limits: Cache Invalidation for External Inputs

The intended behavior is that a computed variable recomputes only when any of its declared State dependencies change; external inputs such as system clocks or file contents are not tracked, so the cache will not update unless a State variable that the computed variable reads is mutated.

Likely explanation

Because Reflex’s computed var system observes reads of State variables during evaluation, it cannot detect changes in non‑State sources; therefore cache invalidation is tied to State mutations, not to time or external file changes.

Confirmed facts

• Cache invalidation occurs when a tracked State var is mutated.
• No standard explicit cache‑invalidation hook for non‑State inputs is documented in the core Reflex computed var API.
• Computed vars rely on implicit dependency tracking via State reads; external inputs are invisible to this tracker.

Steps to verify in your project

1. Define a State with a counter var and a computed var that reads the counter and also accesses Date.now() (or a file‑reading placeholder).
2. Increment the counter and observe that the computed var’s value does not change until the counter is mutated again.
3. Check the installed Reflex package version for any invalidate or refresh method on the computed var object.

Please confirm the Reflex version you are using, as cache‑invalidation APIs may differ between releases.