Question

Are there issues with returning a new instance from an accessor? If so, is there a better approach?

public class Person
{
    private RecIpDet _ipDet;
    public RecIpDet IpDet
    {
        get 
        {                 
            if(_ipDet == null)
                _ipDet = new RecIpDet();
            return _ipDet; 
        }
    } 
}

Answer 1

There are issues, because you never set your field, so you’ll return a new object everytime the property is called.

You should set _ipDet if it’s null, and then return it. This is called lazy instantiation or lazy initialization.

public class Person
{
    private RecIpDet _ipDet;

    public RecIpDet IpDet
    {
        get 
        {                 
            if (_ipDet == null)
            {
                _ipDet = new RecIpDet();
            }

            return _ipDet; 
        }
    } 
}

Keep in mind, this is not thread-safe, so if that’s a factor for you, you’ll need a more robust mechanism. For single threaded applications, this method of lazy instantiation is fine.

If you’re using .NET 4.0 or higher, you can use the Lazy<T> class, which I believe is thread-safe:

public class Person
{
    private Lazy<RecIpDet> _ipDet = new Lazy<RecIpDet>(() => new RecIpDet());

    public RecIpDet IpDet
    {
        get 
        {                 
            return _ipDet.Value; 
        }
    } 
}