C#

<pre lang="c#">
  public Toy this[int toyId, string toyProperty]
  {
   get{return listOfProducts.FirstOrDefault(prod => prod.Id == productId);}
   set{listOfProducts.FirstOrDefault(prod => prod.Id == productId).toyProperty = value;}
  } 

//Change Price Dynamically
item[2, "Price"] = price;
 
//Change Color Dynamically
item[2, "Color"] = color;

MadDashCoder wrote:

In my test project my code does return a Toy object.

MadDashCoder wrote:

This is just a test project to find out how I can use a single set property to change different properties using one LINQ Query.

public object this[int toyId, string toyProperty]
{
  get { return listOfProducts.Single(prod => prod.Id == toyId).toyProperty; }
  set { listOfProducts.Single(prod => prod.Id == toyId).toyProperty = value; }
}

public class Toy
{
   // changing the ID is probably NOT a good idea.
   // put it onto the constructor
   public Toy(int id)
   {
     ID = id;
   }
   public int ID { get; private set; }
   // unless you need ID to be a property (like for data binding)
   // this might be a case for a public readonly field:
   // public readonly int ID;
   public double Price { get; set; }
   public string Color { get; set; }
}

public class Merchandise
{
  public Dictionary<int, Toy> toys;
  public Merchandise()
  {
    var toyList = new List<Toy>();
    // presumably you're actually loading the real data from some other source...
    toyList.Add(new Toy {ID = 1, Price = 10, Color = "Red"});
    toyList.Add(new Toy {ID = 2, Price = 10, Color = "White"});
    toyList.Add(new Toy {ID = 3, Price = 10, Color = "Black"});
    toys = toyList.ToDictionary(t => t.ID);
  }
  
  public string this[int toyId]
  {
   get 
     {
       Toy theToy;
       toys.TryGetValue(toyID, out theToy); // In this case we can ignore the return value
       return theToy;
     }
  }      
}

// this is CLEARLY going to fail!
// You need to use double.TryParse(txtPrice.Text, ...) with appropriate error handling
// to convert it from a string to a double!!!!!
public double price = txtPrice.Text;
public string color = txtColor.Text;
 
public Merchandise item = new Merchandise();
// Before you reference the .Price or .Color properties, 
// you need to validate that item[2] didn't return null!!!

// What you had:

//Change Price Dynamically
// item[2, "Price"].Price = price;
// this  ^^^^^^^^^ was pointless since passing the property name to the indexer didn't accomplish anything
item[2].Price = price;  // with my indexer definition
 
//Change Color Dynamically
// item[2, "Color"].Color = color;
// again ^^^^^^^^^ pointless
item[2].Color = color;

// Instead, more like:
Toy theToy = item[2];
if (theToy != null)
{
  //Change Price Dynamically
  theToy.Price = price;
  //Change Color Dynamically
  theToy.Color = color;
}
else
{
  // report the no such toy with that ID error !!
}

public string this[int toyId, string price, string color]
{
     get
     {
      string result = string.Empty;
       if (color != null)
       {
          result = toyList.FirstOrDefault(toy => toy.ID == toyId).Color;
       }
          else if (price != null)
       {
          result = (toyList.FirstOrDefault(toy => toy.ID == toyId).Price).ToString();
       }
       return result;
    }
    set
    {
       if (color != null)
       {
            toyList.FirstOrDefault(toy => toy.ID == toyId).Color = value;
       }
       else if (price != null)
       {
          toyList.FirstOrDefault(toy => toy.ID == toyId).Price = Convert.ToDouble(value);
       }
    }
}

List<Toy> toys = new List<Toy>();
toys.Add( new Toy() { Id = 1, Color = "Red", Price = 1.20M } );
toys.Add( new Toy() { Id = 2, Color = "Red", Price = 1.20M } );
toys.Add( new Toy() { Id = 3, Color = "Red", Price = 1.20M } );

toys.Single( o => o.Id == 2 ).Color = "Blue";
toys.Single( o => o.Id == 2 ).Price = 3.99M;

toys.ForEach( o => Console.WriteLine( $"{o.Id} {o.Color} {o.Price}" ) );

saeedmir wrote:

FileWatcher can catch registry keys?

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

• the first involved late loading with LoadLibrary from c# ...
• the second involved modify the dll search path using ? SetDllDirectory