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What is an ObservableCollection It is a list that implements the INotifyPropertyChanged under the hood. What does this do Well, put simply it allows the collection to notify the UI anytime there are changes so that the UI can update the visual elements to reflect those changes. So anytime our list changes the UI will re-bind all the items in the list to our ItemsControl or ListBox.

So, then we realize that everything in C# is derived from object, so we rewrite our stack to work with the System.Object type, as shown in Listing 15-2. Listing 15-2. A Stack That Uses System.Object class ObjectStack { object[] dataArray = new object[10]; int currentPos = 0; public void Push(object value) { dataArray[currentPos++] = value; } public object Pop() { return dataArray[--currentPos]; } } We fixed the code duplication issue, but we created another problem. We wanted a stack that held values of a specified type, but we have ended up with a stack that can hold values of any type. Here s a demonstration: ObjectStack stack = new ObjectStack(); stack.Push(2); stack.Push("apple"); stack.Push(8); These statements create an ObjectStack object and then proceed to push a mix of string and int values. When we pop the values, we can t assume that they are of any given type, so, if we try to cast to int, we will get an exception. This is the problem that generic types fix. We can use the C# generic type feature to create classes that work with values of other types, and only those types, but we don t need to know what types they will be when we write our code. Listing 15-3 contains our simple stack, implemented using the generic type feature. Listing 15-3. A Generic Stack class GenericStack<T> { T[] dataArray = new T[10]; int currentPos = 0; public void Push(T value) { dataArray[currentPos++] = value; } public T Pop() { return dataArray[--currentPos]; } }

This section shows you how to use the I2cDevice and I2cBus emulator components to simulate devices connected to the I2C bus. You will also learn how to write a temperature sensor emulator component.

As an example, the following code declares two classes: DaysTemp and Program. The two fields in DaysTemp are declared public, so they can be accessed from outside the class. Method Main is a member of class Program. It creates a variable and object of class DaysTemp, and it assigns values to the fields of the object. It then reads the values of the fields and prints them out. // Declare class DaysTemp