yii\di\Container::has PHP Method

Returns a value indicating whether the container has the definition of the specified name.

See also: set()

public has ( string $class ) : boolean
$class	string	class name, interface name or alias name
return	boolean	whether the container has the definition of the specified name..

    public function has($class)
    {
        return isset($this->_definitions[$class]);
    }

Container