1. (Making Random Number Classes More Generic)

In Chapter 31 and Section 32.2.1 we created a class hierarchy consisting of classes that encapsulate specific random number engines from C++ and Boost Random.
This is an inelegant solution in the long term because of code duplication. The objective of this exercise is to apply a signature-based approach in which we create a class containing a customisable function object (or possibly two) that can be instantiated by functionality in the aforementioned libraries.
What are the advantages of this approach?