> For the complete documentation index, see [llms.txt](https://boxlang.ortusbooks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://boxlang.ortusbooks.com/boxlang-language/reference/built-in-functions/watcher/watchernew.md).

# WatcherNew

Creates and registers a new watcher instance in the watcher service.

The watcher is registered but not started. Call {@code watcherStart( name )} to begin processing filesystem events or {@code start()} on the returned WatcherInstance.

You can register three types of listeners, which BoxLang will automatically wrap into an IWatcherListener implementation:

* {@link Function}: wrapped as a {@code ClosureListener}. Can only handle the {@code onEvent} method.
* {@link IStruct}: wrapped as a {@code StructListener}. Can handle {@code onEvent} and {@code onError} methods.
* {@link String}: treated as a class name and wrapped as a {@code ClassListener}. The class must implement {@code IWatcherListener}.

If {@code name} is omitted or blank, a unique watcher name is auto-generated.

## Method Signature

```
WatcherNew(name=[string], paths=[any], listener=[any], recursive=[boolean], debounce=[long], throttle=[long], atomicWrites=[boolean], delay=[long], errorThreshold=[integer], force=[boolean])
```

### Arguments

| Argument         | Type      | Required | Description                                                                        | Default |
| ---------------- | --------- | -------- | ---------------------------------------------------------------------------------- | ------- |
| `name`           | `string`  | `false`  | Optional watcher name. If blank, an auto-generated name is used.                   |         |
| `paths`          | `any`     | `true`   | A directory path string or an array of directory path strings to watch.            |         |
| `listener`       | `any`     | `true`   | Listener definition: function, struct listener map, or listener class name string. |         |
| `recursive`      | `boolean` | `false`  | Whether to watch subdirectories recursively.                                       | `true`  |
| `debounce`       | `long`    | `false`  | Debounce window in milliseconds.                                                   | `0`     |
| `throttle`       | `long`    | `false`  | Throttle window in milliseconds.                                                   | `0`     |
| `atomicWrites`   | `boolean` | `false`  | Whether atomic write filtering is enabled.                                         | `true`  |
| `delay`          | `long`    | `false`  | Startup delay in milliseconds.                                                     | `0`     |
| `errorThreshold` | `integer` | `false`  | Consecutive listener errors before auto-stop.                                      | `10`    |
| `force`          | `boolean` | `false`  | Whether to replace an existing watcher with the same name.                         | `false` |

## Examples

### Create a new file watcher

```java
w = watcherNew( "myWatcher", getTempDirectory() );
writeOutput( w.getName() );

```

Result: myWatcher

### Watcher with event callback

```java
w = watcherNew( "callbackWatcher", getTempDirectory(), ( event ) => {
    println( event.type() & " on " & event.path() );
} );
writeOutput( isObject( w ) );

```

Result: true

## Related

* [WatcherExists](/boxlang-language/reference/built-in-functions/watcher/watcherexists.md)
* [WatcherGet](/boxlang-language/reference/built-in-functions/watcher/watcherget.md)
* [WatcherGetAll](/boxlang-language/reference/built-in-functions/watcher/watchergetall.md)
* [WatcherList](/boxlang-language/reference/built-in-functions/watcher/watcherlist.md)
* [WatcherRestart](/boxlang-language/reference/built-in-functions/watcher/watcherrestart.md)
* [WatcherShutdown](/boxlang-language/reference/built-in-functions/watcher/watchershutdown.md)
* [WatcherShutdownAll](/boxlang-language/reference/built-in-functions/watcher/watchershutdownall.md)
* [WatcherStart](/boxlang-language/reference/built-in-functions/watcher/watcherstart.md)
* [WatcherStop](/boxlang-language/reference/built-in-functions/watcher/watcherstop.md)
* [WatcherStopAll](/boxlang-language/reference/built-in-functions/watcher/watcherstopall.md)


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