Question

I am trying to implement the strategy pattern. Here is part of my implementation:

public List<string> GetOrderedEmployeeNames(IOrderByStrategy strategy)
{
   return GetEmployeeFullNames().OrderBy(strategy.Order);
}

now every time I call this function I have to write:

var employees = GetOrderedEmployeeNames(new OrderByFamilyName());

Is ‘new-ing up’ the strategy every time the right way or am I implementing this incorrectly?

Answer 1

Not necessarily, although it’s probably not hurting anything to create objects as I’m assuming they’re mostly methods and don’t hold a lot of data.

Some alternatives:

• Implement a StrategyFactory that either creates new instances or hold references to flyweights (small objects that are indexed by some key, like a string)
• Implement the strategies as singletons, but that may be more overhead than you need if there are a lot of strategies.