Question

My code is as follows:

class PropertyRetrievalClass
{
    public delegate object getProperty(string input);

    public object get_Chart_1(string iput)
    {
        Console.WriteLine(iput);
        return "";
    }
    public object get_Chart_2(string iput)
    {
        Console.WriteLine(iput);
        return "";
    }

    public PropertyRetrievalClass() { }
}

public static void Main()
        {
            int i = 1;
            PropertyRetrievalClass obj = new PropertyRetrievalClass();

            Delegate del = Delegate.CreateDelegate(typeof(PropertyRetrievalClass), obj, "get_chart_" + i.ToString());
            string output=  del("asldkl");
        }

It is giving me an error saying “error CS0118: ‘del’ is a ‘variable’ but is used like a ‘method'”

What should I do to use this delegate? I want to call any of “get_chart_1” or “get_chart_2” function and both of them take a string input?

Thanks in advance…

Answer 1

You have two issues in your code.

• A Delegate object is not a method, so you need to use a method on the Delegate object to invoke the method it refers
• The first argument to CreateDelegate should be the delegate type, not the class containing a method you want to invoke.

Full working example:

public delegate void ParamLess();
class SomeClass
{
    public void PrintStuff()
    {
        Console.WriteLine("stuff");
    }
}
internal class Program
{
    private static Dictionary<int, int> dict = null;
    static void Main()
    {
        var obj = new SomeClass();
        Delegate del = Delegate.CreateDelegate(typeof(ParamLess), obj, 
                "PrintStuff", false);
        del.DynamicInvoke(); // invokes SomeClass.PrintStuff, which prints "stuff"
    }
}

In your case, the Main method should look like this:

public static void Main()
{
    int i = 1;
    PropertyRetrievalClass obj = new PropertyRetrievalClass();

    Delegate del = Delegate.CreateDelegate(
        typeof(PropertyRetrievalClass.getProperty), 
        obj, 
        "get_Chart_" + i.ToString());
    string output =  (string)del.DynamicInvoke("asldkl");
}

Update
Note that CreateDelegate is case sensitive on the method name, unless you tell it not to.

// this call will fail, get_chart should be get_Chart
Delegate del = Delegate.CreateDelegate(
        typeof(PropertyRetrievalClass.getProperty), 
        obj, 
        "get_chart_" + i.ToString());


// this call will succeed
Delegate del = Delegate.CreateDelegate(
        typeof(PropertyRetrievalClass.getProperty), 
        obj, 
        "get_Chart_" + i.ToString());


// this call will succeed, since we tell CreateDelegate to ignore case
Delegate del = Delegate.CreateDelegate(
        typeof(PropertyRetrievalClass.getProperty), 
        obj, 
        "get_chart_" + i.ToString(),
        true);