The first special issue of Learning, Media and Technology of 2020, entitled 'Education and technology into the 2020s: speculative futures', presented a series of papers looking to the future of critical research on educational technologies. As we write, just a few months later, with the coronavirus pandemic sweeping around the world, the future appears more uncertain than ever. Global infection and illness, population lockdowns, and mass closures of educational institutions have engulfed countries across the planet in the short time between issues of this journal.The global pandemic is of course not only a serious public health emergency, but a political, economic and social emergency too. Scholarship across myriad disciplines in years to come will examine the medical, political, economic and social factors defining our present moment. Many of these issues will be of interest to readers of Learning, Media and Technology. They include political manoeuvring in relation to the pandemic, from misinformation and economic measures to policies of social distancing, quarantining and isolation; the use and misuse of large-scale data, statistics and visualizations; new forms of digitally mediated work, culture and personal life; surveillance systems for 'contact tracing'; the use of predictive epidemiological modelling; the development of techniques for better public understanding of science; and the political use of behavioural economics as a public pedagogy of population management. Future papers in this journal will be written in the context of changes currently being experienced at planetary scale, and potentially dramatic shifts in the relationships between science, technology and society.In one key area we feel Learning, Media and Technology can and should make a more direct contribution to knowledge and practice during the COVID-19 pandemic: the switch to online and digital education formats and the rise of 'remote' forms of teaching and learning as a consequence of mass closures of schools, colleges and universities. In this moment of pandemic politics, where contests are being fought at multiple scales and levels over the ways to handle and resolve the crisis, distance education has become a widespread matter of concern for political authorities, education businesses, charities, teachers, parents and students alike. Education has become an emergency matter, and along with it, educational technologies have been positioned as a frontline emergency service. In recent years Learning, Media and Technology has become a key publication for critical studies of education and technology. Other outlets have responded to the rapid switch to online education with useful guidance, advice, and references to extant research from promising studies that might support educators to make the best of this new educational emergency. But the need remains for critical reflection on the planetary pivot to digitally mediated remote and distance education.We have no wish to denigrate or criticize online distance education, but rather, the ai...

Object-oriented programming languages allow inter-object aliasing. Although necessary to construct linked data structures and networks of interacting objects, aliasing is problematic in that an aggregate object's state can change via an alias to one of its components, without the aggregate being aware of any aliasing. Ownership types form a static type system that indicates object ownership. This provides a flexible mechanism to limit the visibility of object references and restrict access paths to objects, thus controlling a system's dynamic topology. The type system is shown to be sound, and the specific aliasing properties that a system's object graph satisfies are formulated and proven invariant for well-typed programs.

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 undesirable effects of aliasing. Flexible alias protection can be checked statically using programmer supplied aliasing modes and imposes no run-time overhead. Using flexible alias protection, programs can incorporate mutable objects, immutable values, and updatable collections of shared objects, in a natural object oriented programming style, while avoiding the problems caused by aliasing.

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