26.6. Conclusion of the External Services with Varying Interfaces Problem
A combination of Adapter, Factory, and Singleton patterns have been used to provide Protected Variations from the varying interfaces of external tax calculators, accounting systems, and so forth. Figure 26.8 illustrates a larger context of using these in the use-case realization.
Figure 26.8. Adapter, Factory, and Singleton patterns applied to the design.
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