BitLogger/docs/api/async-logger-child.md

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

name	group	category	update-time	description	key-word
async-logger-child	api	async	20260512	Derive a child async logger by composing the current target with a child target segment.	async logger target public

Async-logger-child

Create a child async logger by composing the current target with another target segment. This is the standard API for hierarchical async logger naming such as app.worker or service.http.client.

Interface

pub fn[S] AsyncLogger::child(self : AsyncLogger[S], target : String) -> AsyncLogger[S] {}

input

• self : AsyncLogger[S] - Parent async logger whose target should be extended.
• target : String - Child target segment or suffix.

output

• AsyncLogger[S] - A new async logger whose default target is the composed child path.

Explanation

Detailed rules explaining key parameters and behaviors

• If the parent target is empty, the child target becomes the full target.
• If the child target is empty, the parent target is preserved.
• If both are non-empty, they are joined with ..
• Queue settings, sink wiring, and runtime behavior are preserved in the returned logger.

How to Use

Here are some specific examples provided.

When Need Hierarchical Async Targets

When subsystem logs should stay grouped under one async namespace:

let logger = async_logger(console_sink(), target="service")
let worker = logger.child("worker")

In this example, worker emits under service.worker while keeping the same async queue behavior.

When Build Deep Async Scopes Step By Step

When deeper target composition should remain readable:

let http = async_logger(console_sink(), target="app")
  .child("http")
  .child("client")

In this example, the final logger target becomes app.http.client.

Error Case

e.g.:

• If target is empty, the returned logger keeps the original parent target.

• If callers need complete replacement rather than composition, with_target(...) should be used instead.

Notes

1. This is the preferred API for hierarchical async logger naming.

2. Composition changes the target only and does not rebuild the queue or sink.