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Either I'm asleep, or I'm missing something - I can't see anything accessing private members outside nested classes ... 
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Hi Griff, I bet my brain-fog right now is thicker than yours 
Of course, you are right that inner nested classes declared 'private are inaccessible in all cases to users of instances of the Outer class.
In this case, it is the fact the inner class 'Something1 (declared 'private) inherits from a public interface that allows the 'AddSomething method in the outer class to both update the private list, and return the new 'ISomething1.
Any other access declaration on the 'Something1 class would mean it is exposed to users of the outer class.
imho, this is part of the weirdness with which nested classes are handled in C#.
And, in my head, now, I see using this method is a way ... awkward ! ... to achieve strong encapsulation, as taught by Saint SOLID.
I eagerly await enlightenment !
cheers, Bill
«The mind is not a vessel to be filled but a fire to be kindled» Plutarch
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Being pedantic, the class implements the interface; it doen't inherit from it.
And there's no actual reference to the nested Something1 class anywhere in that code. You could remove that class, and the code would continue to run and function as expected.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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"pedantic" ? oh, we know what to do with that 
Richard Deeming wrote: And there's no actual reference to the nested Something1 class anywhere in that code.
That's the point: the consumer of an instance of 'OuterClass has no direct access to the plumbing ... except through those publicly exposed methods.
Richard Deeming wrote: You could remove that class, and the code would continue to run and function as expected.
Wrong.
See Harold's response and my reply below.
«The mind is not a vessel to be filled but a fire to be kindled» Plutarch
modified 11-May-22 23:40pm.
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Richard Deeming wrote: The AddSomething and GetSomething methods depend on the interface, not the unused nested class.
Hi, Thanks for looking further into the code !
You are correct that the class definition for 'ISomething1 is not used in the use-case example (it's a fossil from an earlier version), and I will delete that from the code posted here, thanks ! Sorry for any confusion that added.
Those two methods, by design, can only be accessed via an instance of 'OuterClass; while they use the public Interface, I don't see them as "dependent" in the usual sense of that term.
My hypothesis here is limited in scope: does this technique contribute to the encapsulation of the collections of Instances in the outer class that implement the Interface.
This code example is, by design, a terse example.
I also use generics in a way not shown in this example ... imho, does not need to be shown.
The "big picture," imho, is:
1) if you are managing collections of mixed Types (which requires use of Interface), where extensibility ... the user can create new Types that use the Interface ... is important ...
2) and, you want maximum encapsulation of those collections
3) what are good techniques ?
cheers, Bill
«The mind is not a vessel to be filled but a fire to be kindled» Plutarch
modified 12-May-22 6:17am.
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I'm not sure I follow. Are you saying you want to prevent the user from creating new types that implement the interface outside of your assembly?
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Richard Deeming wrote: prevent the user from creating new types that implement the interface outside of your assembly?
That is a very logical next step, but this example is limited to only preventing use of the OuterClass' collections,
In this example, the end user is free to create as many Dogs and Cats as they can afford
p.s. the code gets more interesting when you define an encapsulated instantiator like this:
internal T NewInstance<T>(params object[] args)
where T : class, ISomething1
{
var ttype = typeof(T);
ISomething1 instance = null;
instance = (T) Activator.CreateInstance(ttype, args);
Somethings.Add(instance);
return (T) instance;
}Which is, of course, only one way to handle instantiation; I tend to avoid 'Activator.CreateInstance for reasons I am sure you are aware of.
Returning to the "big picture:" what strategies do you use to increase the encapsulation of classes that maintain collections of mixed types ?
cheers, Bill
«The mind is not a vessel to be filled but a fire to be kindled» Plutarch
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I'm still not entire sure what you're trying to achieve.
If a generic collection contains mixed types, those types must either inherit from a base class, or implement an interface. If the collection class is public, then trying to further restrict the types it can contain to those in the current assembly, or an approved list of assemblies, is usually a sign of a broken design.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Thanks !Richard Deeming wrote: If the collection class is public, then trying to further restrict the type ...
In this case, the 'OuterClass is public; the whole point of this (encapsulation) is allowing access to the internal collections inside that outer class only by methods I expose.
I think you are reading into this some broader issue.Richard Deeming wrote: ... to those in the current assembly, or an approved list of assemblies, is usually a sign of a broken design.
I can easily imagine a scenario where a design of an outer class with private internal classes would be very useful. But, that is not relevant here.
cheers, Bill
«The mind is not a vessel to be filled but a fire to be kindled» Plutarch
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I'd be more impressed if that code actually compiled. But even then I don't really understand what point you are trying to demonstrate.
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Thanks, added the missing 'GetSomething method, and verified it compiles/runs as expected..
Re "point:" please see response to Griff; if there is anyone on the planet I think would instantly see the "point," and be aware of the issue ... and blow my mind with a better technique ...I would pick: you
«The mind is not a vessel to be filled but a fire to be kindled» Plutarch
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If the trick is intended to center around being able to return instances of a private class (which otherwise results in the dreaded "inconsistent accessibility" error) in an at least someone useful way (you can always return it as object, but then what?), then that's known .. by me at least, but I guess in general. The code doesn't really show that in action though. I wouldn't rate that an evil trick, more like "limited usefulness".
Otherwise if it's supposed to be a different trick then I didn't get it.
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Hi Harold, you got it. Thanks !harold aptroot wrote: intended to center around being able to return instances of a private class (which otherwise results in the dreaded "inconsistent accessibility" error)
"Generally known" ? My guess is it is not generally known ... took me quite an effort to locate any discussion of it.
harold aptroot wrote: The code doesn't really show that in action though.
I would argue it does show that, in the use of the Add/Get-Something methods.
"Limited" ? Yes, the example shown here is a bare-bones demo of a technique for encapsulation ... of declared 'private inner classes, and of internal collections of instances of those classes,
I asked for opinions about its use because:
1) it's very unusual in my experience
2) it uses Interface in a very different way than usual.
3) it "feels" awkward to me.
«The mind is not a vessel to be filled but a fire to be kindled» Plutarch
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@Harold
the code gets more interesting when you define an encapsulated instantiator like this:
internal T NewInstance<T>(params object[] args)
where T : class, ISomething1
{
var ttype = typeof(T);
ISomething1 instance = null;
instance = (T) Activator.CreateInstance(ttype, args);
Somethings.Add(instance);
return (T) instance;
}Which is, of course, only one way to handle instantiation; I tend to avoid 'Activator.CreateInstance for reasons I am sure you are aware of.
Returning to the "big picture:" what strategies do you use to increase the encapsulation of classes that maintain collections of mixed types ?
cheers, Bill
«The mind is not a vessel to be filled but a fire to be kindled» Plutarch
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I'm trying to setup a a ToastNotification collection for our toast notifications (which are working, we can create the notifications.)
I'm following this example : Toast Collections - Windows apps | Microsoft Docs
The collection is needed to set a custom name to the notification collections; it usually takes the assembly name. (which can be done but it's a hack)
The method is called after creating the main window.
The defaultManager has a member "User=null"; I'm not sure if it is a valid value for a Default Manager ?
It crashes when getting the GetToastCollectionManager :
System.Exception
HResult=0x80070490
Message=Element not found. (0x80070490)
Source=<Cannot evaluate the exception source>
StackTrace:
<Cannot evaluate the exception stack trace>
This exception was originally thrown at this call stack:
WpfApp1.MainWindow.CreateToastCollection() in MainWindow.xaml.cs
WpfApp1.MainWindow.MainWindow() in MainWindow.xaml.cs
Any ideas ?
private async void SetNotificationCollections()
{
string displayName = "Is Potato";
string launchArg = "NavigateToPotato";
System.Uri iconURI = new System.Uri("ms-appx:///Assets/icon.png");
<pre>
ToastCollection licensingManagerToastCollection = new ToastCollection(
"MyToastCollection",
displayName,
launchArg,
iconURI);
ToastNotificationManagerForUser defaultManager = ToastNotificationManager.GetDefault();
try
{
ToastCollectionManager collectionManager = defaultManager.GetToastCollectionManager();
await collectionManager.SaveToastCollectionAsync(licensingManagerToastCollection);
}
catch
{
return;
}
}</pre>
CI/CD = Continuous Impediment/Continuous Despair
modified 9-May-22 9:32am.
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I don't think calling async methods from a constructor, particularly the main one, is a good idea; like skipping while running.
Try the "Loaded" event instead ("window ready for interaction").
Or try a button event (initially) so you have more control overall.
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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Even if I run non-async, I still crash at the line :
ToastCollectionManager collectionManager = defaultManager.GetToastCollectionManager();
CI/CD = Continuous Impediment/Continuous Despair
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And you're still calling it from the constructor?
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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no, from a button on my form.
CI/CD = Continuous Impediment/Continuous Despair
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Here's the constructor you're calling:
public ToastCollection( string collectionId, string displayName, string launchArgs, Uri iconUri ) {
ApiInformation.TryRaiseNotImplemented(
"Windows.UI.Notifications.ToastCollection",
"ToastCollection.ToastCollection(string collectionId, string displayName, string launchArgs, Uri iconUri)" );
}
Seems perhaps you need to provide your own implementation of said collection.
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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As stated, AFAIK, the crash/exception is not in the collection constructor, it's when calling :
ToastNotificationManagerForUser defaultManager = ToastNotificationManager.GetDefault();
ToastCollectionManager collectionManager = defaultManager.GetToastCollectionManager();
CI/CD = Continuous Impediment/Continuous Despair
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Nope, we decided that it was not worth the effort to make it work.
Maybe we'll look at it in the future.
CI/CD = Continuous Impediment/Continuous Despair
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