Edward D. Willink.
Software Engineering progresses as improvements are made in
languages and methodologies. Significant advances have been made
through the use of Object-Oriented Programming, exploiting the
effective support available in C++. Further evolution of OOP
involving the use of design patterns and aspects requires
additional language support.
Increased flexibility in the declaration of objects is proposed in the form of the FOG (Flexible Object Generator) language, which is a superset of C++ implemented by a translator to C++. FOG generalises C++ syntax and supports compile-time meta-programming and reflection.
The syntax generalisations provide the freedom for programmers to organise code to suit programming concerns and eliminate the need for duplication between interfaces and implementations. Further generalisations define composition policies for repeated declarations so that classes, arrays, enumerations and functions may all be extended. These composition policies support the weaving necessary for re-useable implementation of design patterns and for Aspect Oriented Programming.
A declarative form of meta-programming is supported by derivation rules, which specify how a declaration specified in a base class is to be reinterpreted in derived classes. Automated generation of derived functionality is important for a number of design patterns.
More general meta-programming is provided by elevating most run-time concepts to the meta-level, allowing conditional and iterated manipulation of declarations at compile-time. Compile-time execution enables subsequent run-time code to be optimised to suit application requirements.
The use of meta-variables and meta-functions together with a well-disciplined lexical context for meta-programming and meta-level execution provide a complete replacement for the traditional C preprocessor functionality, satisfying Stroustrup's goal of making Cpp redundant [Stroustrup97]. The new functionality is integrated with the language, fits within an Object-Oriented framework and provides adequate support for modern Software Engineering practices.
The C++ grammar is known to pose a significant parsing challenge and to require context dependent type and template knowledge. This creates considerable difficulties when meta-programming occurs in unresolved contexts. A new approach to parsing C++ has therefore been developed that defers the use of type and template information. This approach leads to a simpler grammar implementation. An extended form of regular expression is presented and used to predict known ambiguities and then show that this simpler grammar covers the C++ grammar.
Full V2 thesis:PDF 1.0MB.
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Edward D. Willink
6 April 2006