Thursday, October 21, 2010

Explicit Interface

// explicit1.cs
interface IDimensions
{
float Length();
float Width();
}

class Box : IDimensions
{
float lengthInches;
float widthInches;

public Box(float length, float width)
{
lengthInches = length;
widthInches = width;
}
// Explicit interface member implementation:
float IDimensions.Length()
{
return lengthInches;
}
// Explicit interface member implementation:
float IDimensions.Width()
{
return widthInches;
}

public static void Main()
{
// Declare a class instance "myBox":
Box myBox = new Box(30.0f, 20.0f);
// Declare an interface instance "myDimensions":
IDimensions myDimensions = (IDimensions) myBox;
// Print out the dimensions of the box:
/* The following commented lines would produce compilation
errors because they try to access an explicitly implemented
interface member from a class instance: */
//System.Console.WriteLine("Length: {0}", myBox.Length());
//System.Console.WriteLine("Width: {0}", myBox.Width());
/* Print out the dimensions of the box by calling the methods
from an instance of the interface: */
System.Console.WriteLine("Length: {0}", myDimensions.Length());
System.Console.WriteLine("Width: {0}", myDimensions.Width());
}
}





// explicit2.cs
// Declare the English units interface:
interface IEnglishDimensions
{
float Length();
float Width();
}
// Declare the metric units interface:
interface IMetricDimensions
{
float Length();
float Width();
}
// Declare the "Box" class that implements the two interfaces:
// IEnglishDimensions and IMetricDimensions:
class Box : IEnglishDimensions, IMetricDimensions
{
float lengthInches;
float widthInches;
public Box(float length, float width)
{
lengthInches = length;
widthInches = width;
}
// Explicitly implement the members of IEnglishDimensions:
float IEnglishDimensions.Length()
{
return lengthInches;
}
float IEnglishDimensions.Width()
{
return widthInches;
}
// Explicitly implement the members of IMetricDimensions:
float IMetricDimensions.Length()
{
return lengthInches * 2.54f;
}
float IMetricDimensions.Width()
{
return widthInches * 2.54f;
}
public static void Main()
{
// Declare a class instance "myBox":
Box myBox = new Box(30.0f, 20.0f);
// Declare an instance of the English units interface:
IEnglishDimensions eDimensions = (IEnglishDimensions) myBox;
// Declare an instance of the metric units interface:
IMetricDimensions mDimensions = (IMetricDimensions) myBox;
// Print dimensions in English units:
System.Console.WriteLine("Length(in): {0}", eDimensions.Length());
System.Console.WriteLine("Width (in): {0}", eDimensions.Width());
// Print dimensions in metric units:
System.Console.WriteLine("Length(cm): {0}", mDimensions.Length());
System.Console.WriteLine("Width (cm): {0}", mDimensions.Width());
}
}

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