C# Source Generators

The source generators feature was adding in .NET 5. They allow you to do interesting things like generate additional source files that will get added to a compilation.
In this video, Kathleen chats with Jared Parsons to find out what source generators are capable of.
[01:15] - What are Source Generators?
[05:24] - Demo: Real-time code generator for classes
[10:54] - Demo: Generating INotifyPropertyChanged
[13:16] - How to learn about building generators?
Introducing Source Generators
devblogs.micro...
Source Generators Cookbook
github.com/dot...
New C# Source Generator samples
devblogs.micro...
Source Generator Samples
github.com/dot...
What’s new in .NET 5
docs.microsoft...
Get your questions answered on the Microsoft Q&A for .NET - aka.ms/dotnet-qa​
Learn .NET with free self-guided learning from Microsoft Learn: aka.ms/learndotnet
#DotNet #Csharp

[@zbecknell]

These are great. We are already using a couple of custom source generators to auto-register gRPC services marked with an attribute... looking forward to see what the community and the folks at Microsoft cook up over time!

[@snapman218]

God, Kathleen interrupting is annoying.

[@leonardomoreno23]

Yesss I got distracted all the time.

[@shaicohen2]

Kathleen you are an amazing host; excellent follow ups. Your passion for source generators shone through! This is an amazing feature! I already have a bunch of ideas I'll probably never get to....

[@Kooshad1]

it didn't seem to match the guy trying to demo/teach to us though, and she keeps interrupting.

[@TheSiddhaartha]

Brilliant! Nice examples! I'm going to use this feature a lot!

[@a-s733]

Great examples. Thank You both...

[@positronalpha]

Ah, it's fully supported by VS now? Awesome! I wrote a generator right after the release and it was not a great experience :).

[@Deltacasper]

How can I use it to generate fake test data based on the bogus framework that is implemented in a class file that generate test data for each entity model and then write it as a file to source code so it can be checked into a git commit?

[@rishabhwadhawan541]

Can i use this and generate unit test code for my source code .? Or can i write a generator that would be able to do so.?

[@chrishaddox5078]

I would like to use something like this to help normalize different developers on our teams code. So many times each developer writes something that looks completely different than everyone else. I like like to use this to help reinforce certain patterns in our application

[@excitingfruit]

That’s what linters are for

[@sujalgupta6177]

Video is very important

[@tristanbellingham6759]

I wonder how it will compare to the ReSharper code generator

[@scdecade]

T4 has been a real pain. This is interesting

[@IIARROWS]

So every class and field has a bunch of utterly useless attributes to them? Great way to keep the IL small.

[@Kirides]

You have access to the source tree. Attributes are just the easiest way to accomplish that functionality. If you wanted you could use comments or anything else. (SyntaxNode trivia)

[@andreasdiermeier8485]

Looking forward to use the new Source Generators. We are using the T4-Templates atm.

[@grumpydeveloper69]

Nice explanation of integrating source generators but I feel the equals example is not that usefull for complex business objects. As soon as there is 1 property that should not be included in the is equal the generator becomes useless, unless you can decorate the properties to be included or excluded. But that can turn out to replace boilerplate code with a lot of decorators.

[@onishirox]

This is amazing, generators can be really useful for repetitive code

[@ibrahimhussain3248]

Wow!!

[@dakotapearl0]

I'm a bit disappointed to not see the AutoEquality generator in the samples. That's the one that really interested me. Is it not ready or is there another reason that it was not included in the samples ? Thanks and great feature. I'm really looking forward to what people produce with this.

[@niton6474]

Uh finally c# gets a Lombok

[@psychotrout]

Nice stuff, thank you!

[@tomkirbygreen]

Magic. Thank you for investing in this! Kudos to all involved in the Generators effort.

[@AlvaroRivoir]

What if I want to document the notify property?

[@krigrtrue]

So is this feature ment to make it easy to do AOP in .net?

[@ulfandersson1732]

I have learned not to use the IS operator because it strives for a bad design. What do you think about this and can we use different design implementations for this such as the visitor pattern or are we stuck with the IS operator in this context?

[@IIARROWS]

I'm interested, what kind of bad design?

[@ulfandersson1732]

​@@IIARROWS Hi, instead of having the implementation of all types in one method with if-statements you can refactor this into virtual methods into a dispatch/visitor-class that implements individual types with method signatures (open/closed principle). Ex. DoSomething(T entity) and do this for all types. It will also reduce the code noise - less code you want to see among other code in that context, like normalizing a relational database. For more information google Design Patterns and Design Principles (SOLID)! You'll be amazed how few patterns and principles needed. And by the way this is design without any specific prog.language, maybe except assembler :).

[@IIARROWS]

@@ulfandersson1732 A visitor pattern is not always applicable, like when the object doesn't know about who needs it. Besides it isn't much more readable with an `is`, and there are times a centralised option is preferred. I'm not convinced, but I will consider a visitor next time I need to do something similar. :) But remember that in .NET calling a method requires a pretty big impact on performance, while the "is" operator doesn't even do any boxing operation.

[@FiveNineO]

This will be very useful. Suddenly records seem a little less useful though 🙂

[@francoismouchati8189]

I don't like magic. I like the idea of writing code that generates code but I want to see the generated coffee in the place where it would have been if I had actually typed it. VS should have console windows to type code that generates code. Like snippets but more advanced.

[@worldisone2429]

Data Annotations will slow down the code

[@IIARROWS]

I don't think about slowing it down (unless using a lot of reflection, maybe), but creating larger files for sure...