Can I use Expression> and reliably see which properties are referenced in the Func?

Question

I\'m writing something in the flavour of Enumerable.Where in that takes a predicate of the form Func. If the underlying T

Answer 1

Yes, you'll be able to see everything directly referenced. Of course, if someone passes

x => ComputeAge(x) > 18

then you won't necessarily know that ComputeAge refers to the Age property.

The expression tree will be an accurate representation of exactly what's in the lambda expression.

Answer 2

Small code example of a visitor that would find directly referenced properties.

public class PropertyAccessFinder : ExpressionVisitor {
    private readonly HashSet<PropertyInfo> _properties = new HashSet<PropertyInfo>();

    public IEnumerable<PropertyInfo> Properties {
        get { return _properties; }
    }

    protected override Expression VisitMember(MemberExpression node) {
        var property = node.Member as PropertyInfo;
        if (property != null)
            _properties.Add(property);

        return base.VisitMember(node);
    }
}

// Usage:
var visitor = new PropertyAccessFinder();
visitor.Visit(predicate);
foreach(var prop in visitor.Properties)
    Console.WriteLine(prop.Name);