BitLogger/docs/api/not.md

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

name	group	category	update-time	description	key-word
not	api	filtering	20260512	Create a reusable record predicate that negates another predicate.	negate filter predicate public

Not

Create a RecordPredicate that returns the logical inverse of another predicate. This helper is the standard way to express exclusion rules without rewriting predicate bodies.

Interface

pub fn not_(predicate : RecordPredicate) -> RecordPredicate {}

input

• predicate : RecordPredicate - Existing predicate to invert.

output

• RecordPredicate - Predicate that returns true when the original predicate returns false.

Explanation

Detailed rules explaining key parameters and behaviors

• not_(...) delegates evaluation to the original predicate and flips the boolean result.
• It does not change the record or short-circuit upstream logic outside the wrapped predicate.
• This helper is useful for excluding known noisy targets, fields, or message patterns.
• It composes well with all_of(...) and any_of(...) for more expressive routing rules.

How to Use

Here are some specific examples provided.

When Exclude One Target Prefix

When everything except one noisy subsystem should pass:

let logger = Logger::new(console_sink())
  .with_filter(not_(target_has_prefix("debug.spam")))

In this example, records under debug.spam... are filtered out.

When Invert A Field Match

When one tenant should be excluded from a shared stream:

let predicate = not_(field_equals("tenant", "internal"))

In this example, all non-internal tenant records continue through the filter.

Error Case

e.g.:

• If the wrapped predicate always returns true, the negated predicate always returns false.

• If the wrapped predicate is too broad, the inversion may unintentionally admit unrelated records.

Notes

1. Prefer not_(...) over duplicating inverse logic inline because the intent is easier to read.

2. Negation is most maintainable when the wrapped predicate is itself narrow and well named.