C# Feature – dynamic

Overview

dynamic defers member binding to runtime, useful for interop or meta-programming, at the cost of type safety.

Introduced In

C# 4 (2010)

Before

object x = GetComObject();
// Reflection or explicit casts required

After

dynamic x = GetComObject();
x.Save(); // resolved at runtime

Annotated Example

dynamic json = System.Text.Json.JsonSerializer.Deserialize<dynamic>("{\"a\":1}");
Console.WriteLine(json.a);

Gotchas & Best Practices

• Avoid in core domain logic; prefer static types.
• Exceptions surface at runtime if members are missing.

Related Features

• Language Fundamentals

Version Notes

• Interacts with nullable contexts; prefer static typing where feasible.