Good class design by example

Question

I am trying to work out the best way to design a class that has its properties persisted in a database. Let\'s take a basic example of a Person. To create a new per

Answer 1

First, I'd put two distinct public constructor to Person:

namespace BusinessLayer
{
    class Person
    {
        public Person(string firstName, string lastName): this(firstName, lastName, DateTime.Now)
        {}

        public Person(string firstName, string lastName, DateTime birthDate)
        {
            FirstName = firstName;
            LastName = lastName;
            DateOfBirth = birthDate;
        }

        public string FirstName { get; set; }
        public string LastName { get; set; }
        public DateTime DateOfBirth { get; set; }
    }
}

this allows you to write both

var p = new Person("Marilyin", "Manson");
var p2 = new Person("Alice", "Cooper", new DateTime(...));

and

var p = new Person { FirstName="Marilyn", LastName="Manson" };

I can't see why you should limit to only one form.

As for the DatabaseComponent I'd strongly suggest to write a method that allows you to save a Person instead of the signature you are implicitly declaring.

That's because, should one day change the way a Person is defined, you'd probably have to change the code in each point you invoke Save() method. By saving just a Person, you only have to change the Save() implementation.

Don't you plan to use an ORM by the way?