Question

I’m using C#, with which I don’t have a lot of experience (I’ve mostly worked with java/php/javascript so far)

What I want is a class in which I save some data, this data can only be written by one other class, but still be read by other classes in the program.

Something like this:

public class DataObtainer{
 DataItem[] Items;
 public DataObtainer(){
  Items = new DataItem[20];
 }
 public void Update(){
  Items[0].SomeProperty = 5;//Being able to change SomeProperty
 }
 //Class only contains properties
 public class DataItem{
  public int SomeProperty;
 }
}

public class AnyOtherClass{
 public void SomeMethod(){
  DataObtainer do = new DataObtainer();
  //What I want:
  DataItem di  = do.items[0];
  Console.WriteLine(di.SomeProperty);//Being able to read SomeProperty
  di.SomeProperty = 5;//Not allow this, not being able to change SomeProperty
 }
}

Answer 1

Use an interface.

public interface IData
{
   string Data1 { get;}
   int MoreData { get;}
}

class Data : IData
{
   public string Data1 { get; set;}
   public int MoreData {get; set;}
}

public class DataObtainer
{
   private Data[] items;
   public DataObtainer()
   {
      items = new Data[20];
   }
   public IEnumerable<IData> Items
   {
      get
      {
         return items;
      }
   }

   public void Update()
   {
      Items[0].MoreData = 5;//Being able to change MoreData
   }
}

public class AnyOtherClass
{
   public void SomeMethod()
   {
       DataObtainer do = new DataObtainer();
       //What I want:
       IData di  = do.Items.First();
       Console.WriteLine(di.MoreData);//Being able to read SomeProperty
       di.SomeProperty = 5;//this won't compile
   }
}

Explaination:

1. Create an interface which you are going to provide to code (IData)
2. Create in implementation of that interface
3. Store in the Obtainer the implementation
4. Give other code access only to the interface. This doesn’t give them access to change values.
5. The calling code can cast to the implementation if it wants, but then they are breaking the contract and all bets are off.