Resilient Oracle PL/SQL

Chapter 8. From What to How: Building Feature Components from the Specification

In Chapter 7, you saw the specification for the invoice creation feature. In this chapter and the next, the coding of the specification commences. It is important to note that the translation of requirements into working code is a creative and iterative process.

Any creative process tends to have a finite range of possible pathways to a correct outcome. In other words, the way I go about it might be different from the route you might take. The end result in both cases should be a solution that produces the same output for the same input with equivalent resilience and performance in both cases.

This flexible approach is not a bad thing; I’m following a method that aims to produce a testable feature and its constituent helpers. The adoption of a solution approach provides a convenient framework for articulating the major deliverable artifacts of the development process, namely descriptions of the following:

1. Simple requirements

2. Schema

3. Features

4. Helpers

5. Tests

In a nutshell, the following should be seen as a set of guidelines and not a prescriptive procedure. If you see a better way to implement one of the steps, then don’t be afraid to go for it.

The Requirements

The desired end result for the mini project is as shown in Figure 8-1.

Figure 8-1. The elements of a feature: helpers and tests