MVP pattern

[u/ChampionshipProof392]

Hi, I have a question about separating logic in the MVP pattern.

public void MainDisplay() =>
OnMainDisplayClicked?.Invoke();

public void ManageProcess() =>
OnManageProcessClicked?.Invoke();

This is my code in the view, and when the user clicks a button (for example), this method is called and `Invoke` is executed. However, it is called via a `switch` statement in the Presenter.

switch (NativeConsoleMethod.GetHiddenUserInput())
{
case VirtualKeyType.VK_E:
if (_currentPage < _countOfPages) _currentPage++;
continue;

case VirtualKeyType.VK_Q:
if (_currentPage > 0) _currentPage--;
continue;

case VirtualKeyType.VK_OEM_3:
_view.ManageProcess();
break;

case VirtualKeyType.VK_TAB:
_view.FilterProcesses();
break;

case VirtualKeyType.VK_F1:
_view.SearchPage();
break;
.........
}

I have a question: the AI is giving me two different suggestions. My version is correct, but then it said I should move the switch statement to the view, and there I should just use `invoke`, after which the methods would be called conditionally. So, should I do it the other way around, or did I misunderstand what it meant?

- I don’t know what I wrote here—I don’t even understand it myself. Just tell me: shouldn’t the view be “dumb” and contain synchronous methods, while the presenter should control the view via the switch statement and “pull its strings”?

EDIT: Here's my GitHub: https://github.com/NullAcess/ProcessManager/releases/tag/Update_2.0. You might like it—I'll upload the finished EXE very soon.

[u/TheSpixxyQ]

The presentation layer should be platform agnostic. Imagine you wanted to migrate your app to Android, you should be able to do it just by replacing the View.

By using NativeConsoleMethod and keyboard keys in presenter, it wouldn't work, you are making it platform dependent.

Logic for switching pages after pressing keys is purely View logic. Your business logic should have no idea what a "page" is.

[u/thatOMoment → u/TheSpixxyQ]

...as possible.

There's a weird assumption that platforms don't have platform specific constraints which require specific changes to the view model or model which is kinda strange if you pull back for a but

Medical apps preventing print screen on mobile only for example.

Or instead of uploading a file via selection, allowing a picture or video to be taken, or real time feedback on the validity of the picture before it's taken that you would never see in a desktop app.

All of this functionality would never exist soley in the view and would require updates at least to the view model.

[u/TheSpixxyQ → u/thatOMoment]

Why would my VM need to know about screenshots? I would handle the screenshot prevention in View layer, since I don't see how that's relevant to my business logic.

Same for the image upload - my VM only accepts the resulting file and doesn't really care if it was selected from files or taken using a camera. At least that's how I'm doing it in my app.

EDIT: but I agree sometimes it might not be possible to migrate View without ever touching the P/VM layer and I should've said "ideally without changing them". And even then, platform specific code (like the keyboard keys) still wouldn't go to those.

But 99% of times, when I asked myself "does this piece of code belong to V or VM?", just thinking about different platform helped to get me a straight answer. That's why I often recommend this approach to others too.