Piece of code analysis

Question

Hi Id like to know what this piece of code is doing please. My comments are next to each expression as to what I think is happening. // Resetting the generic type T and assigning to a local variable t T t = default (T); // Assigning the ExecuteReader method to a local variable named reader in order to get the result of the command. var reader = command.ExecuteReader(); // Whilst the reader variable is reading the rows. if (reader.Read()) // Pass the reader variable to the make method and assign it to t. t = make(reader); // return the value type t. return t; This is the Method signature declaration public static T ReadList (Func make)

Vulpes · Answer

I think you've grasped what it's doing though I've made some slight changes to your comments. // Sets the local variable t to the default value of the type parameter T T t = default(T); // Assigns the return value of the ExecuteReader method to a local variable named reader var reader = command.ExecuteReader(); // Whilst the reader variable is reading the rows. if (reader.Read()) // Passes the reader variable to the make method and assign it's return value to t. t = make(reader); // Returns the value of t. return t; This makes sense because 'make' is a delegate for a method which takes an IDataReader and returns a value of type T and the ReadList method itself also returns a value of type T.

Vulpes · Answer

It's just a local variable declaration like for instance: int t = default(int); which would set 't' to zero which is the default value for ints. The only difference here is that the type is a type parameter T: T t = default(T); If T happened to be int then this line would be equivalent to the earlier one. If T were string then we would have: string t = null; // because default(string) is null

S · Answer

Hi Vulpes With reference to your comment // Sets the local variable t to the default value of the type parameter T T t = default(T); I was under the impression that if a type is declared before a variable ie T t its effectively Getting so that the t reference can be returned with a return statement ie return t; With the opposite being the Setting like so... t = default(T); or even further down in the code // Passing the reader reference to the make method and Setting to local variable t. t = make(reader); Thanks