PCG: A prototype incremental compilation facility for the SAGA environment, appendix F

A programming environment supports the activity of developing and maintaining software. New environments provide language-oriented tools such as syntax-directed editors, whose usefulness is enhanced because they embody language-specific knowledge. When syntactic and semantic analysis occur early in the cycle of program production, that is, during editing, the use of a standard compiler is inefficient, for it must re-analyze the program before generating code. Likewise, it is inefficient to recompile an entire file, when the editor can determine that only portions of it need updating. The pcg, or Pascal code generation, facility described here generates code directly from the syntax trees produced by the SAGA syntax directed Pascal editor. By preserving the intermediate code used in the previous compilation, it can limit recompilation to the routines actually modified by editing

Subclassing errors, OOP, and practically checkable rules to prevent them

This paper considers an example of Object-Oriented Programming (OOP) leading to subtle errors that break separation of interface and implementations. A comprehensive principle that guards against such errors is undecidable. The paper introduces a set of mechanically verifiable rules that prevent these insidious problems. Although the rules seem restrictive, they are powerful and expressive, as we show on several familiar examples. The rules contradict both the spirit and the letter of the OOP. The present examples as well as available theoretical and experimental results pose a question if OOP is conducive to software development at all.Comment: 10 pages, 1 LaTeX file; accompanying C++ and Haskell code and compilation instruction

SAGA: A project to automate the management of software production systems

The SAGA system is a software environment that is designed to support most of the software development activities that occur in a software lifecycle. The system can be configured to support specific software development applications using given programming languages, tools, and methodologies. Meta-tools are provided to ease configuration. The SAGA system consists of a small number of software components that are adapted by the meta-tools into specific tools for use in the software development application. The modules are design so that the meta-tools can construct an environment which is both integrated and flexible. The SAGA project is documented in several papers which are presented

Specifying Reusable Components

Reusable software components need expressive specifications. This paper outlines a rigorous foundation to model-based contracts, a method to equip classes with strong contracts that support accurate design, implementation, and formal verification of reusable components. Model-based contracts conservatively extend the classic Design by Contract with a notion of model, which underpins the precise definitions of such concepts as abstract equivalence and specification completeness. Experiments applying model-based contracts to libraries of data structures suggest that the method enables accurate specification of practical software

Mechanized Verification with Sharing

We consider software verification of imperative programs by theorem proving in higher-order separation logic. Separation logic is quite effective for reasoning about tree-like data structures, but less so for data structures with more complex sharing patterns. This problem is compounded by some higher-order patterns, such as stateful iterators and visitors, where multiple clients need to share references into a data structure. We show how both styles of sharing can be achieved without sacrificing abstraction using mechanized reasoning about fractional permissions in Hoare Type Theory.Engineering and Applied Science