Question

I have in my program a struct type called Square which is used to represent the location (int Rank, int File) of a square on a chess board.

If I assign Square by new Square sq(); say and then I want to reassign it, is it better to do so by

sq = new Square(rank, file);

or by writing an internal Set method and calling Set thus

sq.Set(rank, file);

What I am asking is when you use new on a struct, does the runtime reallocate new memory and call the constructor or does it reuse the existing memory? If it does the former then it would be better to write a Set method to avoid overheads would it not? Cheers.

Answer 1

The traditional thinking these days is the value types should be immutable, so you would not want to have a Set method unless that is returning a new Square object and not mutating the original. As such,

sq = new Square(rank, file);

And

sq = sq.GenerateSquare(rank, file); // renamed Set method from original question to appease comments

Should ultimately perform the same operation.

But given this approach, GenerateSquare would also possibly be better as a static method of Square rather than something depending upon any given instance. (An instance method would be more useful if something about the existing instance was used in the creation of a new instance.)