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Logger-with-min-level

Replace the logger's minimum enabled level. This API controls the first gate checked by log(...) and the convenience level methods.

Interface

moonbit
pub fn[S] Logger::with_min_level(self : Logger[S], min_level : Level) -> Logger[S] {}

input

  • self : Logger[S] - Base logger whose level threshold should change.
  • min_level : Level - New minimum enabled level.

output

  • Logger[S] - A new logger value carrying the updated threshold.

Explanation

Detailed rules explaining key parameters and behaviors

  • log(...) checks is_enabled(level) before constructing and writing a record.
  • Lower-severity records below min_level are skipped without reaching the sink.
  • The returned logger is derived from self; the original logger value is not mutated.
  • This API replaces the stored threshold and does not add a wrapper sink.
  • Only min_level changes. Sink, target, and timestamp behavior stay on the same Logger[S] surface.

How to Use

Here are some specific examples provided.

When Raise Noise Floor In Production

When only warning and error records should be emitted:

moonbit
let logger = Logger::new(console_sink())
  .with_min_level(Level::Warn)

In this example, trace, debug, and info calls are skipped.

The returned logger still uses the same ordinary synchronous logging calls; only the severity gate changes.

When Derive A More Verbose Local Logger

When one branch of code should keep a different threshold:

moonbit
let base = Logger::new(console_sink(), min_level=Level::Info)
let debug_logger = base.with_min_level(Level::Debug)

In this example, the sink is reused while the threshold changes per logger value.

Error Case

e.g.:

  • If min_level is set too high, expected lower-severity diagnostics may disappear.

  • If callers need richer predicate logic than a simple threshold, with_filter(...) should be used instead.

Notes

  1. This API skips disabled levels before any sink write happens.

  2. Use it before adding more complex predicate-based filtering rules.

  3. Use a derived logger value when one branch should tighten the threshold and the base logger should keep its broader level gate.

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