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BitLogger/docs/api/build-library-async-text-logger.md
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2026-06-14 00:23:06 +08:00

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---
name: build-library-async-text-logger
group: api
category: facade
update-time: 20260614
description: Build the library-facing text-console async logger facade from an AsyncLoggerBuildConfig using the configured text formatter directly.
key-word:
- library
- async
- text
- public
---
## Build-library-async-text-logger
Build a `LibraryAsyncLogger[FormattedConsoleSink]` from `AsyncLoggerBuildConfig`. This facade is the library-oriented async builder for text-console runtime output.
### Interface
```moonbit
pub fn build_library_async_text_logger(
config : AsyncLoggerBuildConfig,
) -> LibraryAsyncLogger[FormattedConsoleSink] {
```
#### input
- `config : AsyncLoggerBuildConfig` - Combined sync logger config and async queue/runtime config.
#### output
- `LibraryAsyncLogger[FormattedConsoleSink]` - Library-facing async logger backed by formatted console output.
### Explanation
Detailed rules explaining key parameters and behaviors
- This API delegates to `build_async_text_logger(...)` and then wraps the result as `LibraryAsyncLogger`.
- It always produces a concrete `FormattedConsoleSink` from `config.logger.sink.text_formatter` instead of selecting among sink kinds.
- Unlike `build_library_async_logger(...)`, this facade does not go through the full synchronous configured-logger build path first.
- It uses the selected text-oriented `LoggerConfig` fields directly and therefore does not apply `LoggerConfig.queue` or preserve sync runtime sink controls.
- It is useful when library code wants a narrow async facade while preserving a concrete text-console sink type.
- `to_async_logger()` can recover the underlying full async logger if needed.
### How to Use
Here are some specific examples provided.
#### When Need A Narrow Async Text Logger For Libraries
When a library wants text-console async output and a narrower public type:
```moonbit
let logger = build_library_async_text_logger(
AsyncLoggerBuildConfig::new(
logger=text_console(target="lib.text.async"),
async_config=AsyncLoggerConfig::new(max_pending=4),
),
)
```
In this example, the async text sink shape is preserved under the library facade.
### Error Case
e.g.:
- If callers need sink-kind-driven branching such as JSON console or file-backed async output, they should use `build_library_async_logger(...)` instead.
- Normal async lifecycle expectations still apply if the logger is never run.
### Notes
1. This is the library-side counterpart to `build_application_text_async_logger(...)`.
2. It is most useful when a concrete text-console async sink type matters to the caller boundary.