Tag Archives: class

Generic Geometry Library

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Two months ago Barend Gehrels announced on the OSGeo Discuss list ongoing Open Source project called Generic Geometry Library, GGL in short.

The Generic Geometry Library provides a generic implementation of geometry algorithms, working with geometry types provided by the library itself as well as user-defined types. The library is implemented in C++ programming language with extensive use of elements of metaprogramming like class (type) templates, static polymorphism and compile-time execution. Consequently, GGL is built upon two of the greatest pieces of C++ code ever written by humanity: C++ Standard Library and Boost C++ Libraries.

In my opinion, this project is valuable and have potential which may interest many of us, FOSS4G users and developers. The OSGeo Foundation agreed to host this mailing list ggl@lists.osgeo.org dedicated to discussions development and use of the Generic Geometry Library.

Turing award goes to Barbara Liskov

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Learning principles of Object-Oriented Programming, one of the first and very important thing to understand is a definition of subtype. It’s usually not a big problem to explain it correctly and there are a few descriptions dangling around.

Of course, I have my favourite definition of the relation between supertype and subtype. It is called Liskov Substitution Principle. The LSP reveals existing subtleties that may make understanding of the term of subtype not easy. There is a well-known example presenting potential problems: a squere is a rectangle or may be it is not? Robert Martin has written more about in C++ Report long time ago (PDF). For a C++ programmer, like myself – who cares about design by contract (DbC) – the Liskov Substitution Principle is helpful to understand role of pre-/post-conditions in inheritance.

The Liskov Substitution Principle was formulated by Professor Barbara Liskov (MIT). Two days ago, BBC announced as follows:

The 2009 A. M. Turing Award has gone to Barbara Liskov for her contributions to programming.

(Barbara Liskov wins Turing award, BBC)

Congratulations!