C#: Make your delegates asynchronous from synchronous delegates

Introduction

I wanted to write this post because I realized that a lot of developers have difficulty writing asynchronous delegates. I often see synchronous delegates in code review that could be transformed. So in this post I will show you how to proceede without however going over the usefulness of asynchronism, this is not the purpose of this post.

Synchronous delegates

There are 4 types of delegates in C #, you have delegates that:

• Return a result
• Does not return a result

but also delegates who:

• Take one or more parameters
• Does not take any parameters.

So that’s 4 ways to write a delegate, now let’s see what it looks like:

1. Delegate that doesn’t take any parameter and doesn’t return any value: Action
2. Delegate that takes one or several parameters and doesn’t return any value: Action<Tin>
3. Delegate that doesn’t take any parameter and returns a value: Func<Tout>
4. Delegate that takes one or several parameters and returns a value: Func<Tin, Tout>

Let’s look at a concrete example how this is implemented in practice:

Synchronous to asynchronous delegates

The rule for obtaining a synchronous delegate is simple:
It doesn’t matter if this is an Action or a Func, the asynchronous version will always be a Func returning a Task which gives :

1. Asynchronous Delegate that doesn’t take any parameter and doesn’t return any value: Func<Task>
2. Asynchronous Delegate that takes one or several parameter and doesn’t return any value: Func<Tin, Task>
3. Asynchronous Delegate that doesn’t take any parameter and returns a value: Func<Task<Tout>>
4. Asynchronous Delegate that takes one or several parameters and returns a value: Func<Tin, Task<Tout>>

Example:

That’s it!

I hope this tutorial helped you to understand how to transform your delegates into asynchronous delegates! Happy programming 🙂