---
name: build-async-text-logger
group: api
category: async
update-time: 20260520
description: Build an async logger with a concrete text-console sink from combined logger and async config.
key-word:
    - async
    - text
    - builder
    - public
---

## Build-async-text-logger

Build an async logger directly from `AsyncLoggerBuildConfig`, but keep the concrete sink type as `FormattedConsoleSink` instead of the broader runtime sink wrapper. This helper is the text-console specific counterpart to `build_async_logger(...)`.

### Interface

```moonbit
pub fn build_async_text_logger(config : AsyncLoggerBuildConfig) -> AsyncLogger[@bitlogger.FormattedConsoleSink] {
```

#### input

- `config : AsyncLoggerBuildConfig` - Combined sync logger config plus async queue and flush config.

#### output

- `AsyncLogger[FormattedConsoleSink]` - Config-built async logger backed by a concrete text console sink.

### Explanation

Detailed rules explaining key parameters and behaviors

- This builder converts `config.logger.sink.text_formatter` into a runtime `TextFormatter` and wires it into `text_console_sink(...)`.
- The returned logger inherits `min_level`, `target`, and timestamp behavior from `config.logger`.
- This helper is best suited to text-console output paths where callers want the concrete formatted sink type instead of `RuntimeSink`.

### How to Use

Here are some specific examples provided.

#### When Need Config-built Async Text Console Output

When async queue behavior is config-driven and output should stay on text console formatting:
```moonbit
let logger = build_async_text_logger(
  AsyncLoggerBuildConfig::new(
    logger=text_console(target="async.text"),
    async_config=AsyncLoggerConfig::new(max_pending=4),
  ),
)
```

In this example, the async logger is built around a text console sink rather than the generic runtime sink enum.

### Error Case

e.g.:
- If the logger config was not intended for text-console style output, the broader `build_async_logger(...)` path may be a better fit.

- If the logger is never `run()`, pending records still follow the normal async queue lifecycle rules.

### Notes

1. This API is narrower than `build_async_logger(...)` because it preserves a concrete text sink type.

2. It is the base builder used by the application and library async text facades.