[Bug]: WhenActivated from the Reactive package doesn't provide a CompositeDisposable

[Qonstrukt]

Describe the bug 🐞

While trying to upgrade to ReactiveUI 24, I ran into the issue that DynamicData doesn't seem to be updated yet to use the Primitives. This makes it impossible to upgrade to the Primitives it seems. Fine for now, since I can use the .Reactive packages right? Well... it mostly works, except that WhenActivated apparently already expects to provide a MultipleDisposables instance, while DisposeWith doesn't know what that is.

Step to reproduce

1. Swap out ReactiveUI 23.x with ReactiveUI.Reative 24.x
2. Import the ReactiveUI.Reactive namespace everywhere necessary
3. Error CS1503 : Argument 2: cannot convert from 'System.Action<System.IDisposable>' to 'System.Reactive.Disposables.CompositeDisposable'

The error references the other overload, which is also not compatible of course.

Reproduction

Something simple as this doesn't compile:

using System;
using System.Reactive.Disposables.Fluent;
using ReactiveUI.Reactive;

namespace Test;

public sealed class MyViewModel : ReactiveObject, IActivatableViewModel
{
    public ViewModelActivator Activator { get; } = new();
    
    private string _testProperty;
    public string TestProperty {
        get => _testProperty;
        private set => this.RaiseAndSetIfChanged(ref _testProperty, value);
    }

    public MyViewModel()
    {
        this.WhenActivated(d => {
            this.WhenAnyValue(vm => vm.TestProperty)
                .Subscribe(_ => {})
                .DisposeWith(d);
        });
    }
}

Expected behavior

I would expect to have a WhenActivated overload that supplies an old-fashioned CompositeDisposable.

Screenshots 🖼️

No response

IDE

Rider macOS

Operating system

No response

Version

No response

Device

No response

ReactiveUI Version

24.1.0

Additional information ℹ️

After upgrading I had to do some digging to find there is a ReactiveUI.Primitives repository that includes great documentation for migration. Would be nice to reference this existence from the ReactiveUI release notes! (Or did I miss something?)
Maybe also mention not to migrate yet if you're using DynamicData, which is a recommended dependency.

[Nextra]

While the ecosystem is certainly not ready for many migrations yet (Validation, DynamicData), I don't think this is a bug. Regardless of Primitives flavor, ReactiveUI will migrate to the new disposables.

I believe your issue stems from pulling in the DisposeWith extension from System.Reactive.Disposables.Fluent instead of the MultipleDisposable variant from ReactiveUI.Primitives (or ReactiveUI.Primitives.Reactive in this specific case). Changing the using statement should suffice.

[Qonstrukt]

But I can't load in the ReactiveUI.Primitives namespace as this causes tons of overload conflicts that are near impossible, or at least very annoying to solve.
If it is the case as you say, it might be a while before we could even upgrade to v24. What's the point of the Reactive packages then?

[Nextra]

Yeah, I'd say you need to wait for more of the ecosystem to update before migrating to v24. I've noticed the overload conflicts too, DynamicData and similar dependencies probably define a lot of helpers that will migrate into the Primitives package, regardless of Reactive flavor.

[glennawatson]

There is a PR up with the DynamicData guys at the moment. They take changes at a cautious pace but are keen on adopting.

[glennawatson]

I think in terms of this one I will have to think about the best fit. We might have to talk to the DD guys about getting our dual versions in.

Our original plan with the DD guys was to convert RxUI v24 over to using DD vNext which has a number of performance improvements through design. Just time constraints meant I converted over. I might make some sort of adapter for the ContainerDisposable and implicit operator to make it work in primitives for this case in the mean time.

[Qonstrukt]

That's fair, I figured I'd give it a try. I mean, there's no rush going to v24 of course, but since it's the latest version, newcomers might run into issues as well of course.

I was trying to work around this with my own WhenActivated overload, but it seems more work than just supplying the right disposable is required, as View activation itself seems now broken. Would be nice to have an official work-around in of course!

[Qonstrukt]

After reading some more I think I only now start to understand the idea behind the Reactive packages. I was just trying to move over my existing project to using the Reactive packages as to remain backward compatible. But it seems I should've split off into separate projects? Not sure that's worth the trouble indeed, hah.
I solved most issues by adding a missing using ReactiveUI.Primitives.Reactive;
My IDE had trouble finding it, but after scouring through source and reading the docs again this solved the issue, but only after removing the System.Reactive.* usings as well, and then only importing Unit and others as an alias as suggested in the migration docs.

I'm now running into new problems like (Maui) view activation no longer working, but I guess these could be separate issues. Or could that also be caused by me trying to use the Reactive variants in my single project solution?

[glennawatson]

After reading some more I think I only now start to understand the idea behind the Reactive packages. I was just trying to move over my existing project to using the Reactive packages as to remain backward compatible. But it seems I should've split off into separate projects? Not sure that's worth the trouble indeed, hah. I solved most issues by adding a missing using ReactiveUI.Primitives.Reactive; My IDE had trouble finding it, but after scouring through source and reading the docs again this solved the issue, but only after removing the System.Reactive.* usings as well, and then only importing Unit and others as an alias as suggested in the migration docs.

I'm now running into new problems like (Maui) view activation no longer working, but I guess these could be separate issues. Or could that also be caused by me trying to use the Reactive variants in my single project solution?

If you can give me minimal repos on the maui thing, quick sample app or something, we can have a play around between myself and @ChrisPulman to unblock it. Our priority is to unblock any odd behaviors between the two frameworks.