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February 2009

Windows 7 Installation Experience

Now I'm running Windows 7 on several systems. I'm now running the Beta version on my major system.

The installation experience and stability depends on the hardware. Of course, that's a usual experience with a Beta version.

The best experience is with my newest tablet PC: Fujitsu Siemens Lifebook T5010.
Installation (upgrade from Windows Vista) was smooth, every device is available, so far no major issues. I could also run Microsoft OneCare after telling the application it's running on Windows Vista.

With a slightly older model (Lifebook T4220) installation (upgrade as well) was hanging near the end of the installation during a check of the graphics card. After turning off and on again the installation completed without problems. Checking the Windows Experience Index on this system either results in a hang or a blue screen. However, for normal daily operations this system doesn't have issues.

On a old notebook (HP Compaq NX7000) a new installation of Windows 7 was running fine. For the graphics card just a standard driver was installed during installation. With an update the driver for ATI Mobility Radeon 9000 was installed, and as a result the screen on the display flickered. The display on an external monitor is ok. Rollback the driver. The standard driver just has a Windows Experience Index of 1, but the system is fine for non-display related tasks. I checked the HP Website for drivers, but only Windows XP drivers are offered for this notebook. I used this system for Windows Server 2003 which was fine. It's great that Windows 7 is running on this system as well!

Here is a link for the experience with other systems: Sammelpost: Erfahrungsberichte zu Windows 7 Beta


3. Software Development Day in Wien

Bereits zum dritten mal gibt es den Software Development Day, zum zweiten mal im Euro Plaza! Auch diesmal wieder mit Einblicken in die Zukunft aber auch Informationen über Technologien die bereits jetzt eingesetzt werden sollten!

Max Knor, Andreas Pollak, Georg Drogny und Christian Nagel über Windows Azure, Live Mesh, Silverlight, Windows 7, ADO.NET Data Services, .NET 4.0, C# 4.0 und vieles mehr!

Dienstag, 24. Februar 2009
Konferenzzentrum Euro Plaza in Wien
Details und Anmeldung hier: 3. Development Day in Wien


Separation of Algorithms and Containers (Collections)

The C++ Standard Template Library (STL) separates algorithms from containers. C++ algorithms are defined within the header file can be used with containers depending on the iterator that is needed by the algorithm and the iterator supported by the container. search, search_n, reverse, rotate, copy, count, count_if, find, find_first_of, for_each, max, min, merge are just a few of the algorithms. These are global functions that accept iterators from container classes to iterate all elements.

With .NET 3.5 algorithms are separated from collections as well. Static methods such as Count, Max, Min, First, Skip… are implemented by the Enumerable class. These methods are all extension methods based on the IEnumerable interface and thus can be used with every collection.

Let’s compare the implementation of C++ accumulate with .NET Aggregate. Both have several overloads, but I just want to compare just one. The others are very similar.

C++ aggregate is a template function with four parameters. The first two parameters mark the begin and end of the iteration. This algorithm requires an Input Iterator that implements the operators !=, ++, and *. The third parameter is used as initialization of the aggregation, and the last parameter accepts a function object that has two parameters (BinaryOperation). With a for loop every element that is enumerated is accessed, the binary operation invoked, and the result of the operation accumulated.

Type accumulate(InputIterator _First, InputIterator _Last, Type _Val, BinaryOperation _Binary_op) 
   for (; _First != _Last; ++_First)
      _Val = _Binary_op(_Val, *_First);
   return (_Val);
Using the accumulate method a binary function can be defined that is invoked by accumulate, e.g. a simple multiplier.
int action(int x, int y)
   return x * y;

Calling the accumulate function requires the begin and end for the iteration that is returned from the begin and end methods of the vector class. For multiplying every integer in a vector, the initial value is set to 1, and the address of the action function is passed: int result = accumulate(v1.begin(), v1.end(), 1, action); The .NET version of the C++ accumulate does not differ a lot. Instead of having a begin and end of an iterator, here the IEnumerable interface is used. With C++ iterators just a naming convention is used to give the requirements of the iterator. C++ differentiates input, output, forward, bidirectional, and random access iterators that define what operators must be implemented. With .NET it’s clearly defined what methods must be implemented by the collection by the definition of the IEnumerable interface. The initial value that is passed is similar to the C++ implementation. The last parameter defines the signature of the method that is invoked by Aggregate: a method with two input parameters and a result. Instead of a for loop, .NET makes use of the foreach loop that is converted by the compiler to use the methods of the IEnumerable interface.
public static TAccumulate Aggregate(this IEnumerable source,  
   TAccumulate seed, Func func)
   TAccumulate local = seed;
   foreach (TSource local2 in source)
      local = func(local, local2);
   return local;

Because the Aggregate method is an extension method, it can be invoked like a member of the collection class to aggregate all values from the collection. The functionality that is invoked with every instance can be implemented by using a Lambda expression.
int result = coll.Aggregate(1, (x, y) => x * y);

C++ and .NET have very similar implementations to separate the algorithms from containers. Lambda expressions are not yet available with C++, but will be with a future version C++0x. Algorithms that are available in one place (e.g. C++) can easily be implemented in the other (e.g. .NET).