ProgramGood.Net

Delegates, delegate to another method.  In this example, depending on which person is wired up - Suzanne or Amy.. depends on which method is called when the Get the ingredient button is called.


source code here..delegateIngredients.zip (91.58 KB)

    // can be used to create a variable that can point to any method that takes an int parameter and returns a string
    public delegate string GetSecretIngredient(int amount);

On the form:

        // so variable ingredientMethod of type delegate GetSecretIngredient currently points to a null method
        GetSecretIngredient ingredientMethod = null;

        private void getSuzanne_Click(object sender, EventArgs e)
        {
            // suzanne.MySecretIngredientMethod property returns a new instance of the the GetSecretIngredient delegate thats
            // pointing to her secret ingredient method.
            ingredientMethod = new GetSecretIngredient(suzanne.MySecretIngredientMethod);
        }

When button is pressed it will go to either the suzanne.MySecretIngredientMethod or the amy.AmySecretIngredientMethod

        private void useIngredient_Click(object sender, EventArgs e)
        {
            if (ingredientMethod != null)
                Console.WriteLine("I'll add " + ingredientMethod((int)amount.Value));
            else
                Console.WriteLine("I dont have a secret ingredient");
        }

Good duck example here:
http://stackoverflow.com/questions/687626/the-purpose-of-delegates