feature: Microsoft dependency injection implementation

[weitzhandler]

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

An implementation of IDependencyResolver for Microsoft.Extensions.DependencyInjection.
Fixes #362.
Related to #233.

Please check if the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features) - should be added when merged and package published on NuGet.
• Docs have been added / updated (for bug fixes / features)

[glennawatson]

You need to modify build.cake file.

[glennawatson]

You'll probably have to implement something like a ContractRegistration<TType>, where it has a concurrent dictionary inside with registrations based on contracts. I don't think the scope registrations help in this case.

[glennawatson]

The contract functionality definitely has to remain as is, if a contract exists it's a different "context", this is mostly used by splat/rxui internal functionality.

[glennawatson]

Alright I think that's all the stuff I can find. Rodney will likely do a sweep as well.

Thanks @weitzhandler

[weitzhandler]

Thanks for your comments @glennawatson!
I think I misunderstand a bit how Splat DI works in regards to the contracts:

• What happens if you try to contract-resolve a service that was registered without a contract?
• How is re-registering a type with a contract affecting the original registration?

[glennawatson]

Essentially contracts give you independent registrations of the original one.

so <A, contract null> is a different regristration pool to <A, contract "blah">

[glennawatson]

Contracts are commonly used by users in the scenario where they want to show different views based on contexts on the same view models.

[glennawatson]

public struct ContractInjector<T>
{
   public ConcurrentDictionary<string, T> TypeDictionary = new ConcurrentDictionary<string, T>();
}

public void Register<T>(Func<T> register, string contract)
{
    if (string.IsNullOrWhitespace(contract))
       container.Register<T>(register); // whatever the funciton name is in MSDI 
    else
       container.Register<ContractInjector<T>>(register); // You'll likely have to get any existing ContractInjector's created and input it there against the string.
}

Since this is mostly for RxUI benefit this is sufficient way to fix it.

You can also add extension methods for the MS DI containers so that users can register on both.

Solved.

[weitzhandler]

So no scopes at all?

[glennawatson]

Don't think it helps no, it's a similar concept but not quite what we need. Unless you can see a way of achieving the same results with scopes.

[weitzhandler]

I'll ditch the scopes entirely, because it's wrong. Say we use it, if we have a contract and a type, it becomes a singleton under that contract, whilst when users register with splat they intend to register transients, right?

Anyway, I'll finish it up a bit later. Thank you two for your comments and help!

[glennawatson]

Yeah, a contract is independent of singleton/transient.

[weitzhandler]

Returns null. We shouldn't be throwing exceptions.

Oh, didn't know that. Then I should change the GetRequiredService as well

Btw. Make sure you compile the code before you submit. Also run the build batch file from the root directory too so you know if the unit tests pass.

I did before commiting.

[glennawatson]

It's failing on compile errors btw.

[weitzhandler]

Why doesn't HasRegistration have a contract?

[weitzhandler]

It's failing on compile errors btw.

Sorry about that. I'll make sure to perform this action on every commit. Apologies.

[glennawatson]

I think hasregistration was added later. Probably should have it.

[weitzhandler]

I think hasregistration was added later. Probably should have it.

#372

[glennawatson]

All the resources I found say inheritance of these classes can be a bit dangerous. They aren't really designed for it

[weitzhandler]

Currently it passes all included test cases and some more, but I think more testing can be added to the base DependencyResolver in general. I would like to do that in the near future, as I get some available time.

[glennawatson]

@weitzhandler I think apart from that one last multithreading issue I think this is good to go and like you said further tests/monitoring.

I know this has been a long process compared to some other PRs you done so thanks for your persistence.

[weitzhandler]

Thank YOU for your persistence, not only with this PR, but with the entire repo, and also for teaching me a lot of stuff, I'm so grateful!

[todo]

if list empty remove contract entirely

splat/src/Splat.Microsoft.Extensions.DependencyInjection/MicrosoftDependencyResolver.cs

Lines 327 to 332 in 5c73294

	// TODO if list empty remove contract entirely
	// need to find how to atomically update or remove
	// https://github.com/dotnet/corefx/issues/24246
	return list;
	});
	}

---

This comment was generated by todo based on a TODO comment in 5c73294 in #370. cc @weitzhandler.

[weitzhandler]

Related: #378