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BitLogger/docs/api/logger-is-enabled.md
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2026-05-12 16:06:00 +08:00

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name, group, category, update-time, description, key-word
name group category update-time description key-word
logger-is-enabled api logging 20260512 Check whether a logger would accept a record at a given level.
logger
level
enabled
public

Logger-is-enabled

Check whether a logger would accept a record at the given level based on its current min_level. This API is useful for gating expensive work before building message text or fields.

Interface

pub fn[S] Logger::is_enabled(self : Logger[S], level : Level) -> Bool {}

input

  • self : Logger[S] - Logger whose current minimum level should be checked.
  • level : Level - Candidate severity to test.

output

  • Bool - true when the level is enabled by the logger's current threshold.

Explanation

Detailed rules explaining key parameters and behaviors

  • This method delegates to level.enabled(self.min_level).
  • It only checks logger-level severity gating; it does not evaluate sink filters or patch logic.
  • The result reflects the current logger value, so derived loggers with different min_level settings can return different answers.
  • Use it when message construction or field gathering is expensive enough to justify a pre-check.

How to Use

Here are some specific examples provided.

When Avoid Expensive Debug Preparation

When debug data should only be built if needed:

if logger.is_enabled(Level::Debug) {
  logger.debug(build_debug_snapshot())
}

In this example, expensive string construction is skipped unless debug logging is enabled.

When Inspect Effective Logger Threshold

When code should branch based on current logger behavior:

if logger.is_enabled(Level::Trace) {
  logger.trace("trace path active")
}

In this example, the check mirrors the same severity gate used by log(...).

Error Case

e.g.:

  • If level is below the current minimum threshold, the method returns false.

  • A true result does not guarantee final sink output if later filter logic rejects the record.

Notes

  1. This is a cheap severity check, not a full end-to-end delivery guarantee.

  2. Prefer using it only when precomputing the log payload is meaningfully expensive.