How To Access a property with a given expression

Question

I have the following abstract Class

abstract public class FooActivator<T> where T : class
{
    protected static Expression<Func<Foo, Bar<T>>> ChosenProperty

    public void Activate(T Paramater)
    {
         using (var foo = new Foo)
         {
            foo.ChosenProperty.Method(Paramater) //Obviously wrong, How do you do this?
         }
    }
}

The Idea is that I can Inherit this base class, assign a new value to ChosenProperty in order to tell Activate Which property to call the method on.

Public Class MyClassFooActivator : FooActivator<MyClass>
{
    new static Expression<Func<Foo, Bar<MyClass>>> ChosenProperty = x => x.PropertyOfTypeBarMyClass
}

and now Activate(MyClass Paramater) is ready to be called, and it will call it using

foo.PropertyOfTypeBarMyClass.Method(Paramater)

because that is the Property contained in the Expression.

Obviously I can't do foo.ChosenProperty.Method(Paramater), because ChosenProperty is a Variable of type Expression, but what would be the syntax for selecting whatever property of foo that has been selected by the Expression?

the way you are accessing ChosenProperty that property needs to be public and not at instance level since its static. — terrybozzio, Oct 10 '13 at 16:17
I think you're complicating this more than it should be. Why don't you tell us what is it you're trying to achieve in general? Relevant class names would help as well. — Adi Lester, Oct 10 '13 at 16:31
Try looking here http://stackoverflow.com/questions/10193453/how-can-i-pass-a-property-in-via-a-lambda-expression?rq=1 — Ed Charbeneau, Oct 10 '13 at 16:45

score 3 · Accepted Answer · answered Oct 10 '13 at 16:59

I think what you're looking for is probably something like this:

abstract class FooActivator<T> where T : class
{
    protected abstract Func<Foo, Bar<T>> ChosenProperty { get; }

    public void Activate(T param)
    {
        var foo = new Foo();
        ChosenProperty(foo).Method(param);
    }
}

class MyClassFooActivator : FooActivator<MyClass>
{
    protected override Func<Foo, Bar<MyClass>> ChosenProperty
    {
        get { return x => x.SomeBarMyClassProperty; }
    }
}

Yes! This is exactly what I was looking for. Needed to Drop the `Expression` and just use `Func`. Thank you! — JHixson, Oct 10 '13 at 17:02

How To Access a property with a given expression

1 Answers1