The Ada 95 Rationale comes in four parts. The introductory part is a general discussion of the scope and objectives of Ada 95 and its major technical features. The second part contains a more detailed step by step account of the core language. The third part consists of several annexes addressing the predefined environment and specialized application areas.
Part One: Introduction to Ada 95
This first part is designed to give the reader a general appreciation of the overall scope and objectives of Ada 95 and its main technical features. The opening chapter describes the background to the development of the requirements leading to the new standard. The two main chapters give a technical view of the language from two different standpoints: one highlights the main new features such as type extension, the hierarchical library and the protected type and contains many illustrative examples; the other gives a complete overview of the whole language. The reader is recommended to read this first part before attempting to read the Ada 95 Reference Manual.
Part Two: The Core Language
Part One should have given the reader an overall appreciation of the scope and some of the details of Ada 95. The discussion included some rationale for the main features but did not go into all the details. This second part takes the discussion of the Core language a step further. It covers those important features not discussed in Part One and gives more detail of the rationale including alternatives that were considered and rejected. It is assumed that the reader is familiar with the material in Part One which will be referred to from time to time. It is recommended that this part be read in conjunction with the Ada 95 Reference Manual.
Part Three: The Annexes
The first two parts should have given the reader a good understanding of the Core of Ada 95. This third part describes the material in the Annexes. This includes the predefined environment which is mandatory, as well as the various specialized annexes themselves. It should be noted as a general principle that the annexes contain no new syntax. They are hence largely a description of various packages, attributes and pragmas.
Part Four: The Appendices
This fourth part comprises three appendices which summarize various aspects of the relationship between Ada 83 and Ada 95. Appendix X covers the incompatabilities of which there are few of real significance. Appendix Y gives the main changes betwen the Committee Draft, the Draft International Standard and the final International Standard; it shows that these changes are few and hence that the final language has had the benefit of considerable stability throughout the review periods. Appendix Z is a brief summary of the mapping between the original Requirements and the sections of this rationale where they are addressed; it concludes that Ada 95 meets the Requirements.
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