public void UseOfAction()
{
// Action<TParameter>
// Action is used when we do not have any return type from method.Method with void signature is being used with Action delegate.
// Action<string, int> tempActionPointer;
// Similar to Func delegate, the first two parameters are the method input parameters.
// Since we do not have return object or type, all the parameters are considered as input parameters.
DelegateSample tempObj = new DelegateSample();
Action<string, int> tempActionPointer = tempObj.ThirdTestFunction;
tempActionPointer("hello", 4);
Console.ReadKey();
}
public void UseOfFunc()
{
// Different Flavors of Delegate
// As.NET Framework evolved over a period of time, new flavors have been added to keep implementation simple & optimized.
// By default, you get all the features & functionality with flavors which you get with delegate.Let’s have a look at Func delegate.
// Func < TParameter, TOutput >
// Func is logically similar to base delegate implementation.
// The difference is in the way we declare. At the time of declaration, we need to provide the signature parameter & its return type.
DelegateSample tempObj = new DelegateSample();
Func<string, int, int> tempFuncPointer = tempObj.FirstTestFunction;
int value = tempFuncPointer("hello", 3);
Console.ReadKey();
}
public void UseOfDelegate()
{
// When Do I Use Delegate?
// - Looking at the sample above, a lot of us might think this can be also achieved using Interface or abstract class, then why do we need delegate.
// Delegate can be used in the following scenarios:
// - If you don’t want to pass your interface or abstract class dependence to internal class or layers.
// - If the code doesn't need access to any other attributes or method of the class from which logic needs to be processed.
// - Event driven implementation needs to be done.
DelegateSample tempObj = new DelegateSample();
tempFunctionPointer funcPointer = tempObj.FirstTestFunction;
funcPointer("hello", 1);
Console.ReadKey();
funcPointer = tempObj.SecondTestFunction;
funcPointer("hello", 1);
Console.ReadKey();
}
public void UseOfPredicate()
{
// Predicate <in T >
// Predicate is a function pointer for method which returns boolean value.
// They are commonly used for iterating a collection or to verify if the value does already exist. Declaration for the same looks like this:
// Predicate < Employee > tempPredicatePointer;
// For sample, I have created an Array which holds a list of Employees. Predicate is used to get employee below age of 27:
DelegateSample tempObj = new DelegateSample();
Predicate<Employee> tempPredicatePointer = tempObj.FourthTestFunction;
Employee[] lstEmployee = (new Employee[]
{
new Employee(){ Name = "Ashwin", Age = 31},
new Employee(){ Name = "Akil", Age = 25},
new Employee(){ Name = "Amit", Age = 28},
new Employee(){ Name = "Ajay", Age = 29},
});
Employee tempEmployee = Array.Find(lstEmployee, tempPredicatePointer);
Console.WriteLine("Person below 27 age :" + tempEmployee.Name);
Console.ReadKey();
}