Generic and Inheritance issue - C# Discussion Boards

Ron Beyer31-May-13 12:14

Ron Beyer

31-May-13 12:14

Probably not that hard if you read through the API documentation:

Skype Desktop API Documentation[^]

Kevin Marois31-May-13 12:15

Kevin Marois

31-May-13 12:15

Have you looked at it?

If it's not broken, fix it until it is

Ron Beyer31-May-13 12:22

Ron Beyer

31-May-13 12:22

Briefly, they have an ActiveX control that you can use to issue commands to the Skype system, or if you find one of the wrappers you may be able to roll your own. Tracer looks like it can help you understand the API calls and what is supported, so combining the two and a lot of trial and error it looks like you can interact with Skype via C#.

Generic and Inheritance issue

Kevin Marois31-May-13 12:28

Kevin Marois

31-May-13 12:28

Yss I looked at these earlier, but I really didn't want to reinvent something if someone else already has done it.

Ya, Tracer looks promising. Guiess I'll start there.

Thanks

If it's not broken, fix it until it is

Revolty31-May-13 11:27

31-May-13 11:27

I have the following interfaces, they must inherit in that order, the problem is that i can't make IVideoPlayer to return IVideo as Media. Is this not possible or am I missing something? I'd prefer not to have IAudioPlayer & IVideoPlayer as generic instances - but even if I am - is it possible at all?

I can only see that it would work if IVideoPlayer allso inherited IMediaPlayer<ivideo>, but I cant do that since IAudioPlayer already inherites it? My head hurts. D'Oh! | :doh:

public interface IMedia { }
public interface IAudio : IMedia { }
public interface IVideo : IAudio { }

public interface IMediaPlayer<T> where T : IMedia
{
    T Media { get; }
}

public interface IAudioPlayer : IMediaPlayer<IAudio>
{
    // Media is IAudio
}

public interface IVideoPlayer : IAudioPlayer
{
    // Media must be IVideo!
}

Ron Beyer31-May-13 12:02

Ron Beyer

31-May-13 12:02

What if you did something like...

public interface IVideoPlayer : IMediaPlayer<IVideo>, IAudio
{

}

Maybe there are some implementation details that IVideoPlayer needs from IAudioPlayer, I'm not sure.

Revolty31-May-13 12:52

31-May-13 12:52

I guess you ment IAudioPlayer?
IVideoPlayer would then have both Media as IAudio annd IVideo.

Ambiguity between 'IMediaPlayer<IVideo>.Media' and 'IMediaPlayer<IAudio>.Media'

Revolty31-May-13 13:18

31-May-13 13:18

Got it working. Without generic mess. Big Grin | :-D

Thougt I tryed everything.

public interface _IMedia { }

public interface _IAudio : _IMedia { }

public interface _IVideo : _IAudio { }

public class CMedia : _IVideo
{
}

public interface _IMediaPlayer
{
    _IMedia Media { get; }
}
public interface _IAudioPlayer : _IMediaPlayer
{
    new _IAudio Media { get; }
}
public interface _IVideoPlayer : _IAudioPlayer
{
    new _IVideo Media { get; }
}

public class _CMediaPlayer : _IMediaPlayer
{
    private CMedia m_Media = new CMedia();

    public _IMedia Media { get { return m_Media; } }
}

public class _CAudioPlayer : _CMediaPlayer, _IAudioPlayer
{
    public new _IAudio Media { get { return base.Media as _IAudio; } }
}

public class CVideoPlayer : _CAudioPlayer, _IVideoPlayer
{
    public new _IVideo Media { get { return base.Media as _IVideo; } }
}

Bernhard Hiller2-Jun-13 22:38

Bernhard Hiller

2-Jun-13 22:38

Hm, what about the Liskov principle (see e.g. http://en.wikipedia.org/wiki/Liskov_substitution_principle[^])? Your example somehow reminds me of the square-and-rectangle issue there...
In case that the VideoPlayer can use some code of the AudioPlayer, I'd go for composition instead of inheritance.

Revolty3-Jun-13 11:46

3-Jun-13 11:46

Thanks. It's a good idea, but in my case it was more about hiding properties that isnt 'needed'. Player & Media is allways initzialed as video type.

24 bit to 16 bit on the fly

Keld Ølykke3-Jun-13 20:10

Keld Ølykke

3-Jun-13 20:10

Hi,

You could do it with generics in the following way:

public interface IMedia
{
}
public interface IAudio : IMedia
{
}
public interface IVideo : IAudio
{
}

public interface IMediaPlayer<T> where T : IMedia
{
    T Media
    {
        get;
    }
}

public interface IAudioPlayer<T> : IMediaPlayer<T> where T : IAudio
{
    // Media is IAudio
}

public interface IVideoPlayer<T> : IAudioPlayer<T> where T : IVideo
{
    // Media must be IVideo!
}

public class Class1
{
    public void Example()
    {
        IVideoPlayer<IVideo> videoPlayer = null;
        // not possible:
        //IVideoPlayer<IAudio> videoPlayerPlayingAudio = null;
        IAudioPlayer<IAudio> audioPlayer = null;
    }
}

The problem is that your video player can't be compiled against IVideo and use an audio player compiled against IAudio. Your video player and audio player need to be compiled against the same type.

I don't know what this issue with generics is called, but I always find that generics bread more generics.

Kind Regards,

Keld Ølykke

fachura31-May-13 4:49

fachura

31-May-13 4:49

Hi !

I need help with converting 24 bit input to 16 bit "on the fly" im trying to record audio output, if the format is set to 24 bit depth i have problem with mix it down to one channel (sound is slower) here is the example wchich im using to convert if audio has 32 bit i dont know how to change this code if input has 24 bit

byte[] newArray16Bit = new byte[e.BytesRecorded / 2];
short two;
float value;
for (int i = 0, j = 0; i < e.BytesRecorded; i += 4, j += 2)
{
    value = (BitConverter.ToSingle(e.Buffer, i));
    two = (short)(value * short.MaxValue);

    newArray16Bit[j] = (byte)(two & 0xFF);
    newArray16Bit[j + 1] = (byte)((two >> 8) & 0xFF);
}
byte[] mono = StereoToMono(newArray16Bit);
OutFile.Write(mono);

i found sample code to convert but it returns float[] i need byte:

public float[] Convert24BitToFloat(byte[] input)
{
    int inputSamples = input.Length / 3; // 24 bit input
    float[] output = new float[inputSamples];
    int outputIndex = 0;
    var temp = new byte[4];
    for(int n = 0; n < inputSamples; n++)
    {
        // copy 3 bytes in
        Array.Copy(input,n*3,temp,0,3);
        int sample = BitConverter.ToInt32(temp,0);
        output[outputIndex++] = sample / 16777216f;
    }
    return output;
}

Re: 24 bit to 16 bit on the fly

Bernhard Hiller2-Jun-13 22:42

Bernhard Hiller

2-Jun-13 22:42

Instead of calculating with bytes, go to the samples. Samples are 16bit ints, 24bit ints (which are not well represented in .Net), or 32bit floats. Then do your calculations on the samples. And then convert to the output format.

Calculate code complexity

gastonbed30-May-13 22:49

gastonbed

30-May-13 22:49

I'm given a string which contains an arbitrary amount of code. I want to calculate a number which represents the code complexity of that string. Something like:

int complexity = Lib.FindComplexity(someString);
I realize there are a lot of tools out there that will do this for you. These tools will not work for me, because I want to do it programmatically. I'd love for the library to be in C#, but will work with anything at this point.

Thanks in advance!

Eddy Vluggen30-May-13 23:40

Eddy Vluggen

30-May-13 23:40

gastonbed wrote:
Thanks in advance!

For what? Are you asking how to build this, or stuck with anything else?

The "parts" that build up code-complexity are described here[^]. You'd be writing code to do the same.

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

Alan Balkany31-May-13 4:56

Alan Balkany

31-May-13 4:56

This sounds a lot like the Halting Problem (http://en.wikipedia.org/wiki/Halting_problem[^] ), which is (in general) unsolvable.

Eddy Vluggen31-May-13 6:25

Eddy Vluggen

31-May-13 6:25

Calculating cyclomatic complexity needs not to verify "every possible execution path".

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

Alan Balkany31-May-13 9:33

Alan Balkany

31-May-13 9:33

Cyclomatic complexity is a heuristic that approximates the code's complexity. It doesn't always reflect the true complexity.