Runtime cost of dynamic type resolution in C Sharp (C#)

Introduction

Dynamic type resolution lets a program decide the type of a variable while it runs. This helps write flexible code but can slow the program down a bit.

When you want to call methods on objects without knowing their exact type before running the program.

When working with data from sources like JSON or XML where types are not fixed.

When you want to write code that works with many different types without repeating yourself.

When you need to interact with COM objects or dynamic languages from C#.

When you want to simplify code that uses reflection or late binding.

Syntax

C Sharp (C#)

dynamic variableName = someValue;
variableName.SomeMethod();

The dynamic keyword tells C# to figure out the type when the program runs.

Calls on dynamic variables are checked at runtime, not compile time.

Examples

Adds 5 to the dynamic integer value and prints 15.

C Sharp (C#)

dynamic value = 10;
Console.WriteLine(value + 5);

Accesses the Length property of a string stored in a dynamic variable.

C Sharp (C#)

dynamic text = "Hello";
Console.WriteLine(text.Length);

Calls Add and Count on a List<int> stored as dynamic.

C Sharp (C#)

dynamic obj = new List<int> {1, 2, 3};
obj.Add(4);
Console.WriteLine(obj.Count);

Sample Program

This program shows how dynamic variables work. The program waits until it runs to decide what methods and operations are valid. If a method doesn't exist, it throws a runtime error.

C Sharp (C#)

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        dynamic number = 5;
        dynamic text = "World";

        // Runtime figures out the types and calls correct methods
        Console.WriteLine(number + 10);  // 15
        Console.WriteLine(text.ToUpper()); // WORLD

        // This will cause runtime error if method doesn't exist
        try
        {
            Console.WriteLine(number.NonExistingMethod());
        }
        catch (Microsoft.CSharp.RuntimeBinder.RuntimeBinderException e)
        {
            Console.WriteLine("Runtime error: " + e.Message);
        }
    }
}

Important Notes

Using dynamic adds a small delay because the program checks types while running.

Errors with dynamic variables show up only when the program runs, not when you write the code.

Use dynamic carefully to avoid unexpected runtime errors.

Summary

Dynamic type resolution lets C# decide types while running, making code flexible.

This flexibility comes with a small speed cost because the program checks types at runtime.

Errors with dynamic types appear only when the program runs, so test your code well.