Observer Pattern in C#

Question

Hi,

I have started reading Head First Design Patterns. The language used in the book is Java.

I am now in the Observer pattern chapter, and I am now trying to implement it in C#. I read that we can use IObservable and IObserver interfaces but when I try to use the example in MSDN, I get the following errors:

Error 3 The type or namespace name 'IObserver' could not be found (are you missing a using directive or an assembly reference?) C:\Documents and Settings\xxx\Local Settings\Application Data\Temporary Projects\WeatherStation\Program.cs 48 37 WeatherStation

Error 5 The type or namespace name 'IObservable' could not be found (are you missing a using directive or an assembly reference?) C:\Documents and Settings\xxx\Local Settings\Application Data\Temporary Projects\WeatherStation\Program.cs 61 39 WeatherStation

I am using Visual Studio 2005

Answer 1

you will need to add mscorlib.dll into your reference, which you can get in the .Net component in your project(but I guess there are some issues in Visual Studio 2005 with this assembly)

http://msdn.microsoft.com/en-us/library/dd783449.aspx

regards

joon

Answer 2

C# and java has a few differences, so an easy implementation of the pattern would most likely look something like this:

http://blogs.msdn.com/b/bashmohandes/archive/2007/03/10/observer-pattern-in-c-events-delegates.aspx

Answer 3

Hi cindyak;

The IObserver interfaces is not supported in Visual Studio 2005 and therefore can not be used. Check out Thomas  post for a implementation that does not use IObserver interfaces.

  

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Fernando (MCSD)

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