Reference variable name dynamically

Question

I have a struct that looks like this:

public struct ChannelSettings
{
    public double slider20Hz;
    public double slider25Hz;
    public double slider31_5Hz;
    public double slider40Hz;
}

and I am looping through my user interface objects when a slider value is changed like this:

foreach (Slider slider in grdEqSliders.Children)
{
     // slidername = slider.Name;
     switch(currentChannel)
     {
         case 1:
            // Assign to channel.slidername
            break;
         case 2:
            // Assign to channel.slidername
            break;
         default:
            break;
      }
}

My question is, is there a way for me to get the sliders name then turn it in to something I can reference directly in my structure? For example I would like to turn the slider.Name = "slider_20Hz" in to the variable slider20Hz that I use in my struct.

Well, you can switch on a string; just have the cases be each of those four strings, rather than 1, 2, 3, 4. You could use reflection, but in a case this simple the switch is probably easier. — Servy
– Servy, Commented May 6, 2013 at 19:26
I will have multiple structs though and need to make sure the value is getting put in to the correct one. — Ian Oswald
– Ian Oswald, Commented May 6, 2013 at 19:28
Accessing the appropriate variable (once you have its name) is addressed by this question here - you can do so using reflection. A (possibly) better solution, if it works for your codebase, would be store the doubles in a dictionary - the current var "name" becomes the key. — SWalters
– SWalters, Commented May 6, 2013 at 19:33

MiMo · Accepted Answer · 2013-05-06 20:48:42Z

6

The only way to do that leaving the struct defined as it is now is to use reflection - pretty messy though.

An alternative - changing the definition - is to store the values in a dictionary:

public class ChannelSettings {
  Dictionary<string, double> _values = new Dictionary<string, double>();

   public double slider20Hz {
     get {
       return GetByName("slider20Hz");
     }
     set {
       _values["slider20Hz"] = value;
     }
   }

   . . . 

   public void SetByName(string name, double value) {
     _values[name] = value;
   }

   public double GetByName(string name) {
     double v;
     if (_values.TryGetValue("slider20Hz", out v)) {
       return v;
     }
     return 0.0; // Default value
   }

}

and then to set a value given its name you can write:

channel.SetByName(slider.Name, . . . )

and to get a value:

channel.GetByName(slider.Name)

edited May 6, 2013 at 20:48

answered May 6, 2013 at 19:33

MiMo

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4 Comments

Ian Oswald Over a year ago

I hadn't thought about doing it that way, this should work perfectly. Thanks.

Servy Over a year ago

There is no way to do that leaving the struct defined as it is now. Sure there is; you can do exactly what you've done using reflection if you really want to, although you probably wouldn't want to.

Ian Oswald Over a year ago

How would I call this to get the information back out by passing in the string name?

MiMo Over a year ago

@IanOswald: see updated answer (if I understood correctly your question)

Murkaeus · Accepted Answer · 2013-05-06 19:29:27Z

1

The Slider control, as all FrameworkElements, has a Tag property for these types of situations where you need a property for your own use.

<Slider Tag="slider_20Hz"/>

foreach (Slider slider in grdEqSliders.Children)
{
     slidername = slider.Tag as string;
     ...
}

answered May 6, 2013 at 19:29

Murkaeus

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1 Comment

Ian Oswald Over a year ago

Yes, I am getting that, but then need to reference the variable in the struct with the similar name.

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