static void Main(string[] args)
{
dynamic d = new Duck();
d.Quack();
d.Waddle();
int x = 3, y = 4;
Console.WriteLine(Mean(x, y));
// Runtime Representation of Dynamic
Console.WriteLine(typeof(List<dynamic>) == typeof(List<object>));
Console.WriteLine(typeof(dynamic[]) == typeof(object[]));
object o = new System.Text.StringBuilder();
dynamic dy = o;
dy.Append("hello");
Console.WriteLine(o);
// Dynamic Conversions
dynamic dx = "hello";
Console.WriteLine(dx.GetType().Name);
dx = 123; // No error (despite same variable)
Console.WriteLine(dx.GetType().Name);
}
static void Main(string[] args)
{
//Dynamic Binding: Dynamic binding is useful when at compile time
//you know that a certain function, member, or operation exists,
//but the compiler does not.
//Static Binding vs Dynamic Binding:
//static Binding: the binding is done by the compiler, and the binding
//utterly depends on statically knowing the types of the operands
//Dynamic Binding: A dynamic object binds at runtime based on its
//runtime type, not its compile - time type.
//Custom Binding: Custom binding occurs when a dynamic object implements
//IDynamicMetaObject Provider(IDMOP).
//The Duck class doesn’t actually have a Quack method. Instead, it uses
//custom binding to intercept and interpret all method calls.
dynamic d = new Duck();
d.Quack();
d.Waddle();
//Language Binding: Language binding occurs when a dynamic object does not
//implement IDynamicMet aObjectProvider.
/*The benefit is obvious—you don’t have to duplicate code for each numeric type.
* However, you lose static type safety, risking runtime exceptions rather than
* compile-time errors.*/
int x = 3, y = 4;
Console.WriteLine(Mean(x, y));
//If a member fails to bind, a RuntimeBinderException is thrown. You can think of
//this like a compile - time error at runtime.
//dynamic d = 5;
//d.Hello(); // throws RuntimeBinderException
//Runtime Representation of Dynamic
//There is a deep equivalence between the dynamic and object types.
dynamic x1 = "hello";
Console.WriteLine(x1.GetType().Name);
x1 = 123;
Console.WriteLine(x1.GetType().Name);
//dynamic reference simply enables dynamic operations on the object it
//points to. You can convert from object to dynamic to perform any
//dynamic operation you want on an object:
object o = new System.Text.StringBuilder();
dynamic d1 = o;
d1.Append("hello");
Console.WriteLine(o);//hello
//Dynamic Conversions: dynamic type has implicit conversions to and from all
//to and from all other types
//For the conversion to succeed, the runtime type of the dynamic object must be
//implicitly convertible to the target static type.
int i = 7;
dynamic d2 = i;
long j = d2;//NO cast required (implicit conversion)
//above works because int is implicitly convertible to long
/*The following example throws a RuntimeBinderException because an int is not
* implicitly convertible to a short:
* int i = 7;
* dynamic d = i;
* short j = d; // throws RuntimeBinderException*/
//var vs dynamic
//var and dynamic types bear a superficial resemblance, but the
//difference is deep
//• var says, “Let the compiler figure out the type.”
//• dynamic says, “Let the runtime figure out the type.”
dynamic xd = "hello"; //static type is dynamic, runtime type is string
var yd = "hello"; //static tyoe us string, run time type is string
//int id = xd;//Runtime error(cant convert string to int)
//int jd = yd;//Compile time error (cant convert string to int)
dynamic xd1 = "hello";
var yd1 = xd1; //static type of yd1 is dynamic
//int z = yd1;//Run time error(cant convert string to int)
//Dynamic Calls without Dynamic Receivers
//The dynamic object is the receiver of a dynamic function call
dynamic a = 5;
dynamic b = "watermelon";
Foo(a);
Foo(b);
//static types in dynamic expression
object os = "hello";
dynamic dt = "goodbye";
Foo(os, dt);//os
/*The call to Foo(o,d) is dynamically bound because one of its arguments, d, is
* dynamic. But since o is statically known, the binding—even though it occurs
* dynamically—will make use of that. In this case, overload resolution will pick the
* second implementation of Foo due to the static type of o and the runtime type of d.
* In other words, the compiler is “as static as it can possibly be.*/
//Uncallable Functions
IFoo f = new Foo(); // Implicit cast to interface
f.Test();
//Now consider the situation with dynamic typing:
IFoo fg = new Foo();
dynamic dg = fg;
//dg.Test(); // Exception thrown runtime
/*The implicit cast shown in bold tells the compiler to bind subsequent member calls
* on f to IFoo rather than Foo—in other words, to view that object through the lens
* of the IFoo interface. However, that lens is lost at runtime, so the DLR cannot complete
* the binding.The loss is illustrated as follows:*/
Console.WriteLine(f.GetType().Name); // Foo
Console.ReadLine();
}
