Question

I am self-studying a C# reference and it gives the following information:

1.21.4. Declaring Generic Parameters Generic parameters can be introduced in the declaration of classes, structs, interfaces, delegates (see the upcoming ‘Delegates’ section), and methods. Other constructs, such as properties, cannot introduce a generic parameter, but can use a generic parameter. For example, the property Value uses T:

public struct Nullable<T> {   public T Value {get;} } 

First, I get an error trying to compile this saying that it must contain a body because it is neither abstract nor extern or that automatic parameters must have both get and set accessors.

Second, assuming it is wrong and I correct it by adding ‘set;’, I cannot seem to format a call to it successfully.

Answer 1

I’m not sure if you just picked a bad example for your struct name (since Nullable is a framework struct), but if not, the error is due to the fact that you have no set accessor in your property. Automatic properties (added in C# 3.0) need both a get and set property. So, if you change the code to:

public struct Nullable<T> {   public T Value {get; set; } } 

it should work. In this case, the error had nothing to do with generics. To create an instance, you could use:

Nullable<int> i = new Nullable<int>(); 

This will make it compile. However, as both Jon and Cerebrus has pointed out, it’s probably just an example to show the workings of generics.