Question

I want to write a code snippet which does following thing, like if I have a class let’s say MyClass:

   class MyClass
    {
        public int Age { get; set; }
        public string Name { get; set; }
    }

so the snippet should create following method:

 public bool DoUpdate(MyClass myClass)
  {
        bool isUpdated = false;
        if (Age != myClass.Age)
        {
            isUpdated = true;
            Age = myClass.Age;
        }
        if (Name != myClass.Name)
        {
            isUpdated = true;
            Name = myClass.Name;
        }
        return isUpdated;
    }

So the idea is if I call the snippet for any class it should create DoUpdate method and should write all the properties in the way as I have done in the above example.

So I want to know :

1. Is it possible to do the above ?
2. If yes how should I start, any guidance ?

Answer 1

How about a utility method instead:

public static class MyUtilities
{
    public static bool DoUpdate<T>(
        this T target, T source) where T: class
    {
        if(target == null) throw new ArgumentNullException("target");
        if(source == null) throw new ArgumentNullException("source");

        if(ReferenceEquals(target, source)) return false;
        var props = typeof(T).GetProperties(
            BindingFlags.Public | BindingFlags.Instance);
        bool result = false;
        foreach (var prop in props)
        {
            if (!prop.CanRead || !prop.CanWrite) continue;
            if (prop.GetIndexParameters().Length != 0) continue;

            object oldValue = prop.GetValue(target, null),
                   newValue = prop.GetValue(source, null);
            if (!object.Equals(oldValue, newValue))
            {
                prop.SetValue(target, newValue, null);
                result = true;
            }
        }
        return result;
    }
}

with example usage:

var a = new MyClass { Name = "abc", Age = 21 };
var b = new MyClass { Name = "abc", Age = 21 };
var c = new MyClass { Name = "def", Age = 21 };

Console.WriteLine(a.DoUpdate(b)); // false - the same
Console.WriteLine(a.DoUpdate(c)); // true - different

Console.WriteLine(a.Name); // "def" - updated
Console.WriteLine(a.Age);

Note that this could be optimized hugely if it is going to be used in a tight loop (etc), but doing so requires meta-programming knowledge.