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[.net] C# - How do I create an indexed property?

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I want to be able to create an indexed property on a class. Here's how I'd like to use it:
Sprite.Animations["walk_east"].AddFrame(...)

Where Animations is the property, and "walk_east" is the indexer. I'd rather not have to create a custom collection class and expose it, and I'd also like to avoid using a function that returns an Animation accepting a string if I can use a property for it instead. Here's the code I have. It doesn't compile. I'm following instructions from The C# Station, but it seems like they only apply if the object being indexed is this.
        public Animation Animations[string[] Name]
        {
            get
            {
            }
            set
            {
            }
        }



What am I doing wrong?

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That's because they are showing you how to overload the index operator. A property returns the type you assign it, so that type must have the index operator implemented for itself.

So, if you have an array of animations and you want to address them by name, use a dictionary with the string name of the animation as the key.

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Unlike Managed C++ or C++/CLI, C# does not support other indexed properties than "this". What you normally do is to provide a property that returns an object with an indexer (this-property), for example a dictionary as Washu said or some other class more tailored to your needs, e.g.



class ReadOnlyColors {
Color[] values;

public ReadOnlyColors (Color[] values) {
this.values = values;
}

public Colorthis[int index]{
get { return values[index]; }
}
}


class Data {
ReadOnlyColors backgroundColors;
ReadOnlyColors foregroundColors;


public Data() {
Color[] bg = { Color.Black, Color.Red, Color.Green };
Color[] fg = { Color.White, Color.Yellow, Color.Blue};
backgroundColors = new ReadOnlyColors(bg);
foregroundColors = new ReadOnlyColors(fg);
}


public ReadOnlyColors BackgroundColors{
get{ return backgroundColors; }
}

public ReadOnlyColor ForegroundColors {
get { return foregroundColors; }
}
}

// usage:

Data data = new Data();

Color bg1 = data.BackgroundColors[0];
Color fg1 = data.ForegroundColors[0];



This way BackgroundColors and ForegroundColors can be used like "real" indexed properties.


Regards,
Andre

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