User1109032460 posted
Firstly, Singleton is one of the most mis-used patterns. I'm always sceptical when I see Singleton being used, and require some convincing that it is actually appropriate. In an IoC world, singleton-ness can often be achieved by using an appropriate lifetime
manager with the container.
When you say "Factory pattern" what do you mean?
There is no Factory pattern, per se. There is Abstract Factory and Factory Method, and the commonly used, but not GoF pattern, "Simple Factory".
Both Abstract Factory and Factory Method have their place - just look at the implementation of ADO.NET Managed Providers - and Simple Factory is extremely common. So I would expect to see these cropping up quite regularly.
After all, new is a horror keyword when it comes to building loosely-coupled applications, so some form of factory mechanism is often required in order to minimise its use.
