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New Message on MumbaiUserGroup
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From: Nasha
Message 1 in Discussion
Hi Guys, Nice to know that you guys are appreciating my effort. I have got a lot of
replies for my article on "Differences between Vb.Net and C#". One of the difference
between them is the way Vb.Net and C# handles late binding which is very interesting.
I have got some mails requesting to go in more detail for the same. Here it is !!!!
This is a code snippet showing how to achieve late binding in both Vb.Net and C# .
Step One : Create a Dll called Calc.dll which has a class named MyClass.
Add a function called "Add" which adds two number and returns the result. The
implementaion for it is as follows : namespace Calc
{
public class MyClass
{
public MyClass()
{
} public int Add (int i , int j)
{
return i+j; // adds the two numbers and returns the result
}
}
}
Step Two : Create a Vb.Net project (may be Windows Application project)
which can use the above Dll. Add reference to the above Dll. Add a button to
the form and type and code as shown below Private Sub Button1_Click(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim oMyClass As Object
oMyClass = New Calc.MyClass MessageBox.Show(oMyClass.Add(1, 2))
End Sub Please take not that in the above code.The Type of "oMyClass" object is
Object and NOT Calc. But the complier will still complie this code. (Check the
intellisense for oMyClass object and the you will not see the Add method instead you
will see the default methods of type Sysem.Object) Step Three : Create a
C#.Net project (may be Windows Application project). Dont add reference to the
above Dll. Add two buttons to the form and type and code as shown below:
Button 1: Assembly oAssembly = Assembly.LoadFrom("Calc.dll");
Type[] oTypes = oAssembly.GetTypes(); foreach(Type oTempType in oTypes)
{
MethodInfo[] mi =
oTempType.GetMethods(BindingFlags.DeclaredOnly|BindingFlags.Public|BindingFlags.Instance
);
Object oLateBoundObject = Activator.CreateInstance(oTempType);
MessageBox.Show(mi[0].Invoke(oLateBoundObject,new object[]{1,2}).ToString()); //
Calling the Add Method } Please take a note that the way C# handles late biding
is completely different and is based on Reflection. Button 2: /*
THIS CODE WILL NOT COMPILE
Object oMyClass = new Object();
oMyClass = new DLLProj.MyClass();
MessageBox.Show(oMyClass.Add(1, 2).ToString());
*/ Well if we try to do it the way we did in VB.Net it will simply just not
compile. Uncomment the code for Button 2 and check it out for urself. P.S. --
Please mail me your comments for my articles. I hope this step from my end is helpful
to all of us.
Regards,
Namratha (Nasha)
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