A tutorial on static polymorphism

A good tutorial for template-based “compile-time polymorphism" . It shows how the technique can compete with traditional run-time polymorphism, and how the two can work together.

Generic B-Tree

A generic implementation of Btree. Here the skeleton of the code

C++ Polymorphism., static or dynamic inheritance (part II)

Just a little extension of the previous posting about static polymorphism . Here, I define two different types of distances:

• Distance euclidean d
• Distance cosine d

Both of them works on generic type vectors. In the example, I leveraged boost dense vectors, but you can play with other type of vectors as well.

Here the code

It's official Yahoo teams with OneRiot on real-time search

Yahoo teams with OneRiot on real-time search.

Congrats! Kimbal and Alessio.

C++ Polymorphism., static or dynamic inheritance

Traditional C++ programmers are used to think that everything should be modelled as a collection of classes and objects, organized in a hierarchy.

Inheriting is a great thing, but sometime you don't want to pay the overhead of a virtual method. I mean, anytime you overide a method the compiler will add a new entry in the virtual table and at run-time a pointer must be deferenced. When performance is crucial or when you call a method several times in your code you may want to save this cost.

In these situations, Modern C++ programmers prefer to adop a kind of compile-time variant of the strategy pattern. At compile time, the appropriate class and method is called during template instatiation. In this sense, Policy-based design is very useful when you want to save the cost of the virtual table.

In this example, I wrote a distance class and a method distance which is potentially used very frequently by any clustering algorithm. The method can be either a EuclideanDistance, or any kind of different distance. And there is no need of any additional virtual table, every choice is made at compile time statically.

Here you find the code.

Where Google is going with Enterprise, Real time and other stuff

An interesting interview to Eric Schmidt, it's worth listening it several times ;-)

Can Google Stay on Top of the Web?

Worth reading.

1. Microsoft's (MSFT) new Bing search engine picked up 1.5 percentage points of market share in August to hit 9.5%, according to market researcher Hitwise, while Google's share fell from 71.4% to 70.2%.

2. But longer term, Twitter, Facebook, and related services may pose a more fundamental threat to Google: a new center of the Internet universe outside of search. Twitter, now with 55 million monthly visitors, and Facebook, with 300 million, hint at an emerging Web in which people don't merely read or watch material but communicate, collaborate with colleagues, and otherwise get things done using online services.

3. Meanwhile, Google's very success and size are starting to work against it. In the past year the company has been the target of three U.S. antitrust inquiries and one in Italy. Most recently the Justice Dept. on Sept. 18 said Google's controversial settlement with authors and publishers, which would have allowed it to scan and sell certain books, must be changed to avoid breaking antitrust laws. Even Google's own paying customers—advertisers and ad agencies—say they're eager for alternatives to blunt Google's power. Says Roger Barnette, president of search marketing firm SearchIgnite: "People want a No. 2 that has heft and scale."

4. Most of the search quality group's contributions are less visible because its work is focused mostly on the underlying algorithms, the mathematical formulas that determine which results appear in response to a particular query. Google conducts some 5,000 experiments annually on those formulas and makes up to 500 changes a year