Allocation free delegate or other way to call method by address in C#?

Allocation free delegate or other way to call method by address in C#?

In C#, delegates are a way to refer to a method by its address. However, invoking a delegate can involve allocation, as the delegate is an object that needs to be created on the heap. If you need to call a method by its address in a performance-critical section of your code and you want to avoid allocations, there are a few approaches you can take.

  • Use a static method: If the method you want to call is a static method, you can simply call it directly, without using a delegate. This will avoid the allocation of a delegate object. For example:
public static class MyStaticClass { public static void MyStaticMethod(int arg1, string arg2) { // ... } } // Call the method directly MyStaticClass.MyStaticMethod(42, "Hello");
  • Use a struct to hold the delegate: If you need to pass the delegate around as a value type and avoid heap allocations, you can use a struct to hold the delegate. Structs are value types that can be allocated on the stack, which can be faster than allocating objects on the heap. For example:
public struct MyDelegateHolder { public Action<int, string> MyDelegate; public void Invoke(int arg1, string arg2) { MyDelegate?.Invoke(arg1, arg2); } } // Create a delegate holder and set the delegate MyDelegateHolder holder = new MyDelegateHolder(); holder.MyDelegate = MyMethod; // Call the delegate via the holder holder.Invoke(42, "Hello");

In this example, we define a struct MyDelegateHolder that holds a delegate of type Action<int, string>. The Invoke method of the struct can be used to call the delegate. The struct can be allocated on the stack, which can be faster than allocating a delegate object on the heap.

  • Use a lambda expression: If you need to pass a delegate as an argument to a method or a constructor, you can use a lambda expression to create a delegate inline, without allocating a separate delegate object. For example:
public class MyClass { private Action<int, string> myDelegate; public MyClass(Action<int, string> delegateArg) { myDelegate = delegateArg; } public void InvokeDelegate(int arg1, string arg2) { myDelegate?.Invoke(arg1, arg2); } } // Create an instance of MyClass and pass a delegate via a lambda expression var myObject = new MyClass((arg1, arg2) => { // ... }); // Call the delegate via the object myObject.InvokeDelegate(42, "Hello");

In this example, we define a class MyClass that holds a delegate of type Action<int, string>. The constructor of the class takes a delegate as an argument, which can be passed using a lambda expression. The lambda expression creates the delegate inline, without allocating a separate delegate object.

Examples

  1. "Allocation-free delegate in C#"

    • Description: Explore ways to create a delegate or alternative method to call a function without unnecessary memory allocations.
    // Allocate-free delegate creation Action myMethod = MyMethod;

  2. "Call method by address in C#"

    • Description: Investigate methods to call a method by its address in C# without unnecessary memory allocations.
    // Call method by its address unsafe { delegate*<void> functionPointer = &MyMethod; functionPointer(); }

  3. "C# function pointer without allocation"

    • Description: Search for ways to use function pointers in C# without causing memory allocations.
    // Use function pointer without allocation delegate*<void> functionPointer = &MyMethod; functionPointer();

  4. "Allocation-free method invocation C#"

    • Description: Explore techniques to invoke a method without causing unnecessary memory allocations in C#.
    // Allocation-free method invocation Action myMethod = MyMethod; myMethod();

  5. "Avoiding memory allocations when calling methods in C#"

    • Description: Learn best practices to avoid memory allocations when calling methods in C#.
    // Use a delegate to avoid memory allocations Action myMethod = MyMethod; myMethod();

  6. "C# call function without creating a delegate"

    • Description: Search for ways to call a function without explicitly creating a delegate in C#.
    // Call function without creating a delegate unsafe { ((delegate*<void>)&MyMethod)(); }

  7. "Fast method invocation in C#"

    • Description: Explore fast and efficient methods for invoking methods in C# without causing unnecessary memory allocations.
    // Efficient method invocation Action myMethod = MyMethod; myMethod();

  8. "Direct method invocation in C#"

    • Description: Look for ways to directly invoke a method in C# without using delegates and without memory allocations.
    // Direct method invocation MyMethod();

  9. "Low-level method invocation in C#"

    • Description: Explore low-level, memory-efficient approaches to invoke methods in C# without unnecessary allocations.
    // Low-level method invocation unsafe { delegate*<void> functionPointer = &MyMethod; functionPointer(); }

  10. "C# avoid memory allocations when invoking action"

    • Description: Learn how to invoke an Action or delegate without causing memory allocations in C#.
    // Invoke Action without memory allocations Action myMethod = MyMethod; myMethod();

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