Find all methods with an attribute using GeneratorExecutionContext

Im kind of new with source generators and Im trying to find all the methods marked with my attribute but can't approach, it would love if there was way to be guided by it

I don't know if what I want to do is possible or not but I assume it is

I want to find all classes that inherit from an abstract class and have a method decorated with my attribute

was kind of curious if this

var classInheritingFromBaseClass = context.Compilation.SyntaxTrees
                .Where(classes => classes is NetworkBehaviour);

gets me all classes that inherit from NetworkBehaviour

Rider warns me about it

Yeah, this isn't the way to go about it

You have a couple of misconceptions, and a couple of major issues in that snippet 🙂

First: do not iterate all syntax trees

That will have terrible performance

Do I need to get root first?

No, abandon this approach altogether

Oh...

You're completely on the wrong track 🙂

Are you following some tutorial?

Im trying to generate code for methods with an attribute but not sure how to do that

I followed some sample code

but it was doing something completely different

Where did that sample code come from?

Oh this isn't sample code from a tutorial

I was trying to figure it out myself

Oh

but was talking about previously

I would suggest looking at some samples 🙂

Oh okay, any recommendations in mind? I'll try to look for more.

First and foremost: use incremental generators, not V1 generators

Second: if you can, use the https://sourceroslyn.io/#Microsoft.CodeAnalysis/SourceGeneration/Nodes/SyntaxValueProvider_ForAttributeWithMetadataName.cs,78 API that's going to be part of 2022.4

Oh okay never knew there was a difference

It will make what you're trying to do significantly simpler

using foreach?

No

It's an entirely different strategy of making a generator

Oh okay will look into it

Instead of implementing ISourceGenerator, you should implement IIncrementalGenerator

Oh got it

but kind of confused about the difference

but I guess I'll find out

Then, you use the various providers on the context to create a pipeline

ISourceGenerator was V1. IIncrementalGenerator is V2

Oh interesting

A pipeline is like a LINQ query

so I guess I won't need ISourceGenerator anymore?

To use the above api, you'd do something like this:

context.SyntaxProvider.ForAttributeWithMetadataName("Fully.Qualified.Name", (node, token) => /* Syntax checks for whether you want to look at this method */, (context, token) => /* Transform into the next step of your pipeline */) ... // More steps of your pipeline

Sorry noob question but how can I check which version of Microsoft.CodeAnalysis.Analyzer nuget packet this is in?

I can't find the declaration in the source code of the nuget version I got

It's in 4.4.0

Ie, latest prerelease

ah

That's why I said use it if you can, but I understand if you can't

Since it's not released yet

But the API is specifically designed for this case and will make your code ~10-100 orders of magnitude more performant (no exaggeration)

Oh wow.. okay I'll give it a shot

Would I be able to target it with .netstandard 2.0 or at least .net 4.0?

You must target standard2.0 in your generator

Oh okay that works for me then, also got another noob question, what's usually the best way to add the preview of the package to my project?

Ive never done it before

Well, I know how to do it in VS

Not sure about rider

since I dont think I can get it from nuget atm

You can get it from nuget

Oh how would it be done in vs usually?

Oh okay

There's a checkbox for allow prerelease

https://www.nuget.org/packages/Microsoft.CodeAnalysis.CSharp/4.4.0-1.final is the version

Oh okay got it. :D

Right now I'm having one issue where even tho I got the right nuget package installed it seems the method doesn't exist

so I'm trying to find where it's declared and Im relatively new with rider so need to look up some shortcuts

oh nvm for some reason I had the old wrong version reference in my csproj

Can I ask you what you mean by transform here? (context, token) => /* Transform into the next step of your pipeline */)

Extract the data you need from the syntax and put it in a model, likely a simple record type

Oh right

so I'm planning on sending all the parameter into a buffer

so I guess I'd extract the parameters of the method

and their type

did I understand that correctly?

You need to extract all the data you need to generate code

got it

BTW, #roslyn is a channel 🙂

Oh I should check that out. :D

is it better to ask there with roslyn related questions?

Yes

got it will do from now on :D

rider also has a checkbox for preview versions… even a checkbox for unlisted packages if you like to live dangerously 😂