Applying the Singleton Pattern to the Case Study
In Chapter 14, I encapsulated the rules about taxes within strategy objects. I have to derive a CalcTax class for each possible tax calculation rule. This means that I need to use the same objects over and over again, just alternating between their uses.
For performance reasons, I might not want to keep instantiating them and throwing them away again and again. And, while I could instantiate all of the possible strategies at the start, this could become inefficient if the number of strategies grew large. (Remember, I may have many other strategies throughout my application.) Instead, it would be best to instantiate them as needed, but only do the instantiation once.
The problem is that I do not ...
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