Union of Two Objects Based on Equality of Their Members

Question

Let us start with a class definition for the sake of example:

public class Person
{
    public string FirstName;
    public string LastName;
    public int Age;
    public int Grade;
}

Now let's assume I have a List called people containing 3 objects:

{"Robby", "Goki", 12, 8}
{"Bobby", "Goki", 10, 8}
{"Sobby", "Goki", 10, 8}

What I am looking for is some way to retrieve the following single Person object:

{null, "Goki", -1, 8}

where fields which are the same in all objects retain their value while fields which have multiple values are replaced with some invalid value.

My first thought consisted of:

Person unionMan = new Person();
if (people.Select(p => p.FirstName).Distinct().Count() == 1)
    unionMan.FirstName = people[0].FirstName;
if (people.Select(p => p.LastName).Distinct().Count() == 1)
    unionMan.LastName = people[0].LastName;
if (people.Select(p => p.Age).Distinct().Count() == 1)
    unionMan.Age = people[0].Age;
if (people.Select(p => p.Grade).Distinct().Count() == 1)
    unionMan.Grade = people[0].Grade;

Unfortunately, the real business object has many more members than four and this is both tedious to write and overwhelming for someone else to see for the first time.

I also considered somehow making use of reflection to put these repetitive checks and assignments in a loop:

string[] members = new string[] { "FirstName", "LastName", "Age", "Grade" };
foreach (string member in members)
{
    if (people.Select(p => p.**member**).Distinct().Count() == 1)
        unionMan.**member** = people[0].**member**;
}

where **member** would be however reflection would allow the retrieval and storage of that particular member (assuming it is possible).

While the first solution would work, and the second I am assuming would work, does anyone have a better alternative solution to this problem? If not, would using reflection as described above be feasible?

Union of Two Objects Based on Equality of Their Members

3 Answers