Strategy Pattern with no 'switch' statements?

I don't think your switch here in your demo app is actually part of the strategy pattern itself, it is just being used to exercise the two different strategies you have defined.

The "switches being a red flag" warning refers to having switches inside the strategy; for example, if you defined a strategy "GenericDrawer", and had it determine if the user wanted a SquareDrawer or CircleDrawer internally using a switch against a parameter value, you would not be getting the benefit of the strategy pattern.

You can also get rid of if with help of a dictionary

Dictionary<string, Func<IDraw> factory> drawFactories = new Dictionary<string, Func<IDraw> factory>() { {"circle", f=> new CircleDraw()}, {"square", f=> new SquareDraw()}}();

Func<IDraw> factory;
drawFactories.TryGetValue("circle", out factory);

IDraw draw = factory();

Strategy isn't a magic anti-switch solution. What it does do is give modularise your code so that instead of a big switch and business logic all mixed up in a maintenance nightmare

• your business logic is isolated and open for extension
• you have options as for how you create your concrete classes (see Factory patterns for example)
• your infrastructure code (your main) can be very clean, free of both

For example - if you took the switch in your main method and created a class which accepted the command line argument and returned an instance of IDraw (i.e. it encapsulates that switch) your main is clean again and your switch is in a class whose sole purpose is to implement that choice.

The following is an over engineered solution to your problem solely for the sake of avoiding if/switch statements.

CircleFactory: IDrawFactory
{
  string Key { get; }
  IDraw Create();
}

TriangleFactory: IDrawFactory
{
  string Key { get; }
  IDraw Create();
}

DrawFactory
{
   List<IDrawFactory> Factories { get; }
   IDraw Create(string key)
   {
      var factory = Factories.FirstOrDefault(f=>f.Key.Equals(key));
      if (factory == null)
          throw new ArgumentException();
      return factory.Create();
   }
}

void Main()
{
    DrawFactory factory = new DrawFactory();
    factory.Create("circle");
}