BitLogger/docs/api/library-logger-warn.md

name, group, category, update-time, description, key-word

name	group	category	update-time	description	key-word
library-logger-warn	api	facade	20260613	Emit a warn-level record through a LibraryLogger facade using the warning severity shortcut.	library facade warn public

Library-logger-warn

Emit a warn-level record through the library-facing sync logger. This is the convenience wrapper for log(Level::Warn, ...) on LibraryLogger[S].

Interface

pub fn[S : Sink] LibraryLogger::warn(
  self : LibraryLogger[S],
  message : String,
  fields~ : Array[Field] = [],
) -> Unit {

input

• self : LibraryLogger[S] - Library-facing logger that should emit the warning record.
• message : String - Warning message text.
• fields : Array[Field] - Optional structured fields attached to the record.

output

• Unit - No return value. The record is handled according to the current threshold and wrapped sink pipeline.

Explanation

Detailed rules explaining key parameters and behaviors

• This helper delegates to log(Level::Warn, ...) on the wrapped logger.
• Warning records are useful for abnormal but non-fatal conditions.
• Per-call target override is not exposed here; use log(...) when that is required.
• All logger wrappers still participate normally in the write path.

How to Use

Here are some specific examples provided.

When Signal A Recoverable Library Problem

When an operation degraded but still continued:

logger.warn("cache miss ratio increased")

In this example, the event is elevated above normal information without being treated as a hard failure.

When Attach Structured Warning Context

When a warning should include machine-readable detail:

logger.warn("retry scheduled", fields=[field("attempt", "3")])

In this example, the warning remains easy to filter and inspect later.

Error Case

e.g.:

• If the logger minimum level is above Warn, the call returns without writing a record.

• If a target override is needed at this call site, use log(...) instead of this shortcut.

Notes

1. Use this helper for degraded or suspicious states that do not stop execution.

2. Warning logs are often a practical signal threshold for alerting or separate routing.