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In order to increase our ability to use measurement to support software development practise we need to do more analysis of code. However, empirical studies of code are expensive and their results are difficult to compare. We describe the Qualitas Corpus, a large curated collection of open source Java systems. The corpus reduces the cost of performing large(More)
Aliasing is endemic in object oriented programming. Because an object can be modified via any alias, object oriented programs are hard to understand, maintain, and analyse. Flexible alias protection is a conceptual model of inter-object relationships which limits the visibility of changes via aliases, allowing objects to be aliased but mitigating the(More)
The relationships between objects in object-oriented programs are as important as the objects themselves. Unfortunately, most object-oriented programming languages provide little support for such relationships, leaving the task of implementing them entirely to the programmer. Relationships are typically hard-coded into the participating classes, resulting(More)
Modern programming languages have little or no support for querying objects and collections. Programmers are forced to hand code such queries using nested loops, which is both cumbersome and inefficient. We demonstrate that first-class queries over objects and collections improve program readability, provide good performance and are applicable to a large(More)
Large amounts of Java software have been written since the language's escape into unsuspecting software ecology more than ten years ago. Surprisingly little is known about the structure of Java programs in the wild: about the way methods are grouped into classes and then into packages, the way packages relate to each other, or the way inheritance and(More)
Many contemporary object-oriented programming languages support first-class queries or comprehensions. These language extensions make it easier for programmers to write queries, but are generally implemented no more efficiently than the code using collections, iterators, and loops that they replace. Crucially, whenever a query is re-executed, it is(More)