C#•2mo ago

Dependency Injection Question

I'm working on a music player which can play both local and streamed media. To play the files, I'm using a library which has a SoundPlayer class. (https://lsxprime.github.io/soundflow-docs/getting-started/) To handle file vs streaming, I'm using a switch statement inside my SoundEngine class:

switch (fileType)
  {
    case eFileType.File:
      _player = new SoundPlayer(new StreamDataProvider(File.OpenRead((string)path)));
    break;
            
    case eFileType.Stream:
      _player = new SoundPlayer(new StreamDataProvider((Stream)path));
      break;

switch (fileType)
  {
    case eFileType.File:
      _player = new SoundPlayer(new StreamDataProvider(File.OpenRead((string)path)));
    break;
            
    case eFileType.Stream:
      _player = new SoundPlayer(new StreamDataProvider((Stream)path));
      break;

I shouldn't be newing up classes inside my SoundEngine, and want to use DI instead. However, since a user can play different files while the (which must be passed into the _player variable), I can't use constructor injection. Is there another way to handle this?

SoundFlow Documentation

Getting Started with SoundFlow

Learn how to install the library, set up your development environment, and write your first SoundFlow application.

25 Replies

Keswiik•2mo ago

can you show more of your codebase? hard to really tell what's going on if all we can see is a switch statement

VortacOP•2mo ago

Here's my SoundEngine class: https://paste.mozilla.org/PUT8LaoC and my Program.cs: https://paste.mozilla.org/NziKCgHZ SoundEngine is accessed from a Terminal user interface controlled by a class called Tui https://paste.mozilla.org/k6fzaXZs

Keswiik•2mo ago

personally, I think I'd change Play to take a Stream and not an object and if you want di, you can then create a SoundPlayerFactory with a public SoundPlayer Generate(Stream source) {...} method don't know what ePlayerStatus and eFileType are, but using lower case values to start type names doesn't follow normal c# conventions

VortacOP•2mo ago

Enums

Keswiik•2mo ago

also, is there a reason you need your own player status enum? why not expose the PlaybackState of your sound player? it would let you simplify your PlayPause function to do something like:

        switch (_player.PlaybackState)
        {
            case PlaybackState.Playing:
                _player.Pause();
                break;
            case PlaybackState.Paused:
            case PlaybackState.Stopped:
                _player.Play();
                break;
            default:
                throw new ArgumentOutOfRangeException();
        }

        switch (_player.PlaybackState)
        {
            case PlaybackState.Playing:
                _player.Pause();
                break;
            case PlaybackState.Paused:
            case PlaybackState.Stopped:
                _player.Play();
                break;
            default:
                throw new ArgumentOutOfRangeException();
        }

VortacOP•2mo ago

How can I expose the playback state to the UI? Right now, my UI class takes an IPlayer instance, with SoundEngine being the implementation. The actual player is a third-party library initialized inside SoundEngine I created the enum so I could manage the playbackstate from my UI

Keswiik•2mo ago

you could use a nullable PlaybackState property like

public PlaybackState? PlaybackState => _player?.PlaybackState

public PlaybackState? PlaybackState => _player?.PlaybackState

granted there are downsides to an approach like this if you ever change sound libraries you may have to refactor parts of your UI but if that is not an issue you could use to above to keep things simple the added benefit that a null PlaybackState would let you know that you have not attempted to play any files and could accurately show that in your UI

VortacOP•2mo ago

I'd like to try and keep the UI separate from the implementation

Keswiik•2mo ago

in that case, you can still simplify your playback logic a little by using a fallthrough like I am

VortacOP•2mo ago

I'm getting an unexpected token on the nullable ? and a Cannot resolve symbol '_player' error

Keswiik•2mo ago

are you using an older version of c#?

VortacOP•2mo ago

.NET 8.0

Keswiik•2mo ago

show code then, should be valid unless you messed up syntax somewhere

VortacOP•2mo ago

    private readonly MiniAudioEngine _soundEngine;
    private SoundPlayer _player;
    public string LastFileOpened { get; set; }
    
    public PlaybackState? => _player?.PlaybackState;

    private readonly MiniAudioEngine _soundEngine;
    private SoundPlayer _player;
    public string LastFileOpened { get; set; }
    
    public PlaybackState? => _player?.PlaybackState;

Keswiik•2mo ago

oh im dumb, made a typo in my example lol PlaybackState? PlaybackState i gave you a property with a missing name :PatrickDab:

VortacOP•2mo ago

Ahh, thank you! On the switch statement, I'm getting a cannot resolve error on PlaybackState

        switch (_player.PlaybackState)

        switch (_player.PlaybackState)

Keswiik•2mo ago

change it to State https://github.com/LSXPrime/SoundFlow/blob/master/Src/Components/SoundPlayer.cs it's an open source project so you can always look at the classes and see what you can use

VortacOP•2mo ago

I had tried that, but then the switch case doesn't work:

case PlaybackState.Playing:

case PlaybackState.Playing:

Saying it cannot resolve symbol

Keswiik•2mo ago

https://github.com/LSXPrime/SoundFlow/blob/master/Src/Enums/PlaybackState.cs it's a public type, should be able to use it make sure you're not missing a using statement for it

VortacOP•2mo ago

Another thing is to access it inside my UI, it seems I need to modify my ISoundEngine interface to add

PlaybackState PlaybackState { get; }

PlaybackState PlaybackState { get; }

Which adds a dependency on SoundFlow to my Interface. Shouldn't I try to avoid that?

MODiX•2mo ago

Vortac

I'd like to try and keep the UI separate from the implementation

Quoted by

<@138557476462264320> from #Dependency Injection Question (click here)

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Keswiik•2mo ago

probably, but you were asking about how to use PlaybackState so i answered you can still use your own enum with the switch statement i showed just make sure you update your state property as well

VortacOP•2mo ago

I'm confused. My original switch statement used my own enum, which kept the implementation separate

Keswiik•2mo ago

yes, and I made suggestions before you mentioned wanting to keep implementations separate my switch statement was intended to show you how to avoid copy-pasting code between cases my switch statement with fallthrough, using your enum, would look like this:

        switch (WhateverYourStatusPropertyIs)
        {
            case ePlayerStatus.Playing:
                _player.Pause();
                // update WhateverYourStatusPropertyIs
                break;
            case ePlayerStatus.Paused:
            case ePlayerStatus.Stopped:
                _player.Play();
                // update WhateverYourStatusPropertyIs
                break;
            default:
                throw new ArgumentOutOfRangeException();
        }

        switch (WhateverYourStatusPropertyIs)
        {
            case ePlayerStatus.Playing:
                _player.Pause();
                // update WhateverYourStatusPropertyIs
                break;
            case ePlayerStatus.Paused:
            case ePlayerStatus.Stopped:
                _player.Play();
                // update WhateverYourStatusPropertyIs
                break;
            default:
                throw new ArgumentOutOfRangeException();
        }

VortacOP•2mo ago

Thanks!

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