CODEWITHSUNDEEP
c#.netdynamic
SnickersAreMyFave
SnickersAreMyFave

Reputation: 5143

C# 4.0: Dynamic, Inheriting from DynamicObject

Let's say I have this:

dynamic foo = new Foobar();

And I have this:

public class Foobar : DynamicObject
{

}

The question is, is it possible to override members of DynamicObject so that this code:

string name = new Foobar().Name

Does not throw an Exception at run-time? I want to return default for name's if Name is not a member.

Possible? What do I need to override?

Upvotes: 6

Views: 7984

Answers (3)

Sergey Teplyakov
Sergey Teplyakov

Reputation: 11647

Something like this:

class Foobar : DynamicObject 
{
    private object m_object;

    public ExposedObjectSimple(object obj)
    {
        m_object = obj;
    }

    public override bool TryInvokeMember(
            InvokeMemberBinder binder, object[] args, out object result)
    {
        //Trying to find appropriate property
        var property = m_object.GetType().GetProperty("Name", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);
        if (property != null)
        {
            result = (string)property.GetValue(b, null);
            return true;
        }

        result = SomeDefaultName;
        return true;
    }
}

Upvotes: 3

Ray Henry
Ray Henry

Reputation: 905

Override TryGetMember (and TrySetMember). Classes derived from the DynamicObject class can override this method to specify dynamic behavior for operations such as getting a value for a property.

http://msdn.microsoft.com/en-us/library/system.dynamic.dynamicobject.aspx http://msdn.microsoft.com/en-us/library/system.dynamic.dynamicobject.trygetmember.aspx

Upvotes: 7

Reed Copsey
Reed Copsey

Reputation: 564333

You need to override TryGetMember. Just set to always return true, and provide the default if the member does not exist.

Upvotes: 1

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