ASP.NET setting and getting viewstate in a property - asp.net

Question

can someone please explain me the code written below
public IList<GetProductPrice> CurrentPage
{
get { return ViewState["CurrentPage"] as List<GetProductPrice>; }
set { ViewState["CurrentPage"] = value; }
}

Answer 1

It is called a Property. They generate a getter and setter functions when compiled:
List<GetProductPrice> GetCurrentPage(){
return ViewState["CurrentPage"] as List<GetProductPrice>;
}
void SetCurrentPage(List<GetProductPrice> value) {
ViewState["CurrentPage"] = value;
}
//i think its actual get_.. but it doesn't matter for the example
So its generates ease of use getter setters. which you can just call by using:
var test = CurrentPage; //compiled to var test = GetCurrenctPage();
CurrentPage = test; //compiled to SetCurrentPage(test);
If you leave the getter and setter empty like this:
public int CurrentPage
{
get;
set;
}
it will also generate a backing field on the class where it stores the data:
private int _currentPage;
public GetCurrentPage(){ return _currentPage }
public SetCurrentPage(int value) { _currentPage = value }
Why do we do this?
Using getters and setters is a very old best practise from java (where ide's would have an option to generate them). But this would lead to a lot of boilerplate code!
In C# they try to counter this by adding these properties. But why do we need getters and setters? For example if you want to be notified when a value changes (to mark the classes it self as dirty). I think entity framework uses it to track if a model is changed otherwise it wont do a db update call. There are also other usefull tools that inject code in properties on compile time. to add extra functionality.
How not to use it:
using properties to return HttpContext.Current Is a dangerous one because you secretly depend on the HttpContext so try not to do this at any time!
Generally its also bad practise to use it when the code inside the get or set is very heavy (very instensive). Its bad practise because someone else using the code might think he is just setting a property/field while actually some very heavy code is executed. its best practice to make a special function for this instead and private the getter/setter:
public int Property {get; private set; }
public SetProperty(int value){
//intensive code here:
Property = value;
}

Answer 2

This property is letting the consumer of the property to use it like Local collection without referring the ViewState in the code. It will make the code simple and easy to use.
get { return ViewState["CurrentPage"] as List<GetProductPrice>; }
Here the ViewState object ViewState["CurrentPage"] is converted to list of GetProductPrice
set { ViewState["CurrentPage"] = value; }
Here the List is assigned to ViewState["CurrentPage"]

Answer 3

This code will only work in a controller, where ViewState is a property. This CurrentPage property provides a statically-typed way to access a certain ViewState item through that property.
So instead of sprinkling ViewState["CurrentPage"] as List<GetProductPrice> all over your controller code where you want to access the "current page", you can now simply use the CurrentPage property.
Of course "current page" is a term made up by the developer who chose to name things like this, I don't see how a List<GetProductPrice> has a relation to the "current page".