Question

I have a class defined as

class P
{
        public List<P> children; 
        public int Val1;
        public int Val2;
}

As you can see the class has a list of objects of the same class. I instantiate the class and fill the list:

P myp = new P { children = new List<P> {new P {Val1 = 1, Val2 = 1}, new P {Val1 = 2, Val2 = 2}}};

Now, if I want to sum up the values of the children’s fields and place them in the appropriate parent field I can do

foreach (var p in myp.children)
{
        myp.Val1 += p.Val1;
        myp.Val2 += p.Val2;
}

which seems efficient but uglier or I can do

myp.Val1 = myp.children.Sum(p => p.Val1);
myp.Val2 = myp.children.Sum(p => p.Val2);

which is more readable but iterates through the list twice.

Is there a beautiful AND efficient way of doing this? Or am I stuck with the foreach?

Answer 1

Sometimes we developers get neurotic about the silliest things. I’ve been there way too much. I don’t think there is any reason to change it.

Still, if you want to, here is an idea:

class P
{
    public List<P> children;
    public int Val1;
    public int Val2;

    public void Add( P p )
    {
        this.Val1 += p.Val1;
        this.Val2 += p.Val2;
    }
}

And then you can do…

myp.children.ForEach( myp.Add );