aamirOnline (my weblogs)

As being a component or library developer one has to consider many aspects of component development. One of the such aspect is providing a feature which is not natively supported by the language in which components is being developed. For example Optional parameters feature of VB.Net. Everyone knows that optional parameters are not possible in C#. Yes, that's true, well there is a way out. Just apply OptionalAttribute defined in the System.Runtime.InteropServices to the parameter that you want to make optional. That's it, you are done...

Here is an example...

public string GetName([Optional]string param)
{
if (param == null) //Check for null.
param = "Aamir"; //Set the default value.
return param;
}

Andyes, remember C# optional parameters are not optional in C#. This is the way of creating optional parameter for vb.net.

.Net provide many ways to instantiate an object. Here I am going to enlighten some of them.

1. When Type is loaded or available.
   This is the most basic way of instantiating an object, To instantiate and object use new keyword, following the type’s constructor.
   
   Object obj = new Object();


2. When type is not loaded or available
   
   If you want to instantiate object dynamically when Type (class, struct, etc…) is not available or not loaded into the assembly then Activator comes at your service. You can create an instance using Activator.CreateInstance(…) and Activator.CreateInstanceFrom(…) methods. These methods provide many overloads for creating instances from various parameters. Some of examples given below.
   
1. Using Type’s object:
   
   IObject obj = (IObject) Activator.CreateInstance( type, new object [] {"a", 10});
   
   Here the first parameter is an object's Type, and the second parameter is an array of arguments which are supplied to the constructor of given Type.
   


2. Using Assembly and class name as string
   
   ObjectHandle handle = Activator.CreateInstance( "AssemblyName","NamespaceName.ClassName" );
   IObject obj = (IObject)handle.Unwrap();
   
   There are other overloads also please check out MSDN document…

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