Set a watcher function

# Zookeeper::setWatcher

(PECL zookeeper >= 0.1.0)

Zookeeper::setWatcher — Set a watcher function

### 説明

public Zookeeper::setWatcher ( callable `$watcher_cb` ) : bool

### パラメータ

`watcher_cb`

  A watch will be set at the server to notify the client if the node changes.

### 返り値

成功した場合に `TRUE` を、失敗した場合に `FALSE` を返します。

### エラー / 例外

This method emits PHP error/warning when parameters count or types are wrong or fail to set watcher.

警告

Since version 0.3.0, this method emits ZookeeperException and it's derivatives.

### 参考

- Zookeeper::exists() - Checks the existence of a node in zookeeper synchronously
- Zookeeper::get() - Gets the data associated with a node synchronously
- ZookeeperException