mirror of
https://github.com/Nanaloveyuki/BitLogger.git
synced 2026-05-30 15:42:25 +00:00
Nanaloveyuki
82 lines
2.2 KiB
Markdown
82 lines
2.2 KiB
Markdown
---
|
|
name: logger-with-target
|
|
group: api
|
|
category: logging
|
|
update-time: 20260512
|
|
description: Replace the default target carried by a logger so later records inherit a new target namespace.
|
|
key-word:
|
|
- logger
|
|
- target
|
|
- namespace
|
|
- public
|
|
---
|
|
|
|
## Logger-with-target
|
|
|
|
Replace the logger's default target. This API is the simplest way to retarget a logger instance so later log calls inherit a new namespace without passing `target?` on every call.
|
|
|
|
### Interface
|
|
|
|
```moonbit
|
|
pub fn[S] Logger::with_target(self : Logger[S], target : String) -> Logger[S] {}
|
|
```
|
|
|
|
#### input
|
|
|
|
- `self : Logger[S]` - Base logger whose default target should be replaced.
|
|
- `target : String` - New default target namespace.
|
|
|
|
#### output
|
|
|
|
- `Logger[S]` - A new logger value carrying the updated target.
|
|
|
|
### Explanation
|
|
|
|
Detailed rules explaining key parameters and behaviors
|
|
|
|
- The returned logger keeps the same sink, min level, and timestamp settings.
|
|
- This API replaces the default target instead of composing it.
|
|
- Per-call `target?` arguments can still override the default target on individual log calls.
|
|
- The original logger value is not mutated.
|
|
|
|
### How to Use
|
|
|
|
Here are some specific examples provided.
|
|
|
|
#### When Need A Stable Namespace For One Subsystem
|
|
|
|
When one logger should always emit under a fixed target:
|
|
```moonbit
|
|
let logger = Logger::new(console_sink())
|
|
.with_target("service.auth")
|
|
|
|
logger.info("started")
|
|
```
|
|
|
|
In this example, later records inherit `service.auth` unless a call overrides the target explicitly.
|
|
|
|
#### When Reuse One Sink Across Different Namespaces
|
|
|
|
When multiple subsystem loggers share the same sink:
|
|
```moonbit
|
|
let base = Logger::new(console_sink())
|
|
let worker = base.with_target("worker")
|
|
let api = base.with_target("api")
|
|
```
|
|
|
|
In this example, target routing stays explicit without duplicating sink construction.
|
|
|
|
### Error Case
|
|
|
|
e.g.:
|
|
- If `target` is empty, the logger remains valid and later records default to an empty target.
|
|
|
|
- If callers actually need parent-child target composition, `child(...)` is the better API.
|
|
|
|
### Notes
|
|
|
|
1. Use this API for replacement, not hierarchical composition.
|
|
|
|
2. It is useful when one sink serves several target namespaces.
|
|
|