Strategy Pattern

The Strategy Pattern swaps an algorithm at run time behind one interface, instead of branching on a type inside the caller.

One job has several ways to do it. Retrying a failed request can mean not retrying at all, waiting a fixed delay, or backing off exponentially. Which one is right depends on the environment, the endpoint, and sometimes the customer.

Written directly, it becomes a branch inside the class that makes the call:

if (policy == NONE)             { /* give up */ }
else if (policy == FIXED)       { /* wait 100ms and try again */ }