public function listen($callback) {
		if ($this->listening) {
			$this->connection->read(function ($line) use ($callback) {
				$this->checkForError($line);
				$change = $this->parseChangeLine($line);
				if ($change) {
					return $callback($change);
				}
			});
		}
	}
public function listen($callback) {
		if ($this->listening) {
			$this->connection->read(function ($line) use ($callback) {
				$this->checkForError($line);
				$change = $this->parseChangeLine($line);
				if ($change) {
					return $callback($change);
				}
			});
		}
	}
public function listen ( $ callback ) { if ( $ this -> listening ) { $ this -> connection -> read ( function ( $ line ) use ( $ callback ) { $ this -> checkForError ( $ line ) ; $ change = $ this -> parseChangeLine ( $ line ) ; if ( $ change ) { return $ callback ( $ change ) ; } } ) ; } }
Listen actively to all incoming changes

Note that this is a blocking process and will cause the process to block forever if not explicitly terminated

@param callable $callback
Listen actively to all incoming changes