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How can I restrict who can make changes using interfaces?

I have a IHasTag interface, a TaggableItem class that implements IHasTag and a TaggingManager class which I want to make it the only one responsible for setting or clearing the Tags but I've been struggling all day trying to implement but with no luck.
How can I make this possible?
public class TaggableItem : TaggingManager.IHasTag
{
public string Tag { get; } // read only
}
public class TaggingManager
{
public interface IHasTag
{
string Tag { get; }
}
private List<IHasTag> _taggedItems = new();
public void TagItem(IHasTag item, string tag)
{
item.Tag = tag; // not working
_taggedItems.Add(item);
}
public void ClearAllTags()
{
foreach (var item in _taggedItems)
{
item.Tag = "": // not working
}
_taggedItems.Clear();
}
}
EDIT
I followed Thomas' suggestion and this is what I end up doing. I know it's not perfect, though. Thank you all for your advices.
public interface ITaggable
{
string? Tag { get; }
}
public interface ISelectable
{
bool IsSelected { get; }
}
public interface IItem : ITaggable, ISelectable
{
}
public class Item : IItem
{
protected Item() { }
public bool IsSelected { get; set; }
public string Tag { get; set; } = string.Empty;
// 'Item' will be created here returning IItem.
// So, unless you 'cast' it, you can't set 'Tag' or 'IsSelected'.
public static IItem CreateItem() => new Item();
}
public class SelectionManager
{
protected List<object> _items = new();
public void Select(ISelectable item)
{
if (item is Item selectable)
{
selectable.IsSelected = true;
_items.Add(item);
}
}
public void Unselect(ISelectable item)
{
if (item is Item selectable)
{
selectable.IsSelected = false;
_items.Remove(item);
}
}
}
public class TaggingManager
{
private List<object> _items = new();
public void Tag(ITaggable item, string tag)
{
if (item is Item taggable)
{
taggable.Tag = tag;
_items.Add(item);
}
}
public void Untag(ITaggable item)
{
if (item is Item taggable)
{
taggable.Tag = string.Empty;
_items.Remove(item);
}
}
}

My suggestion would be to have two interfaces for two purposes: reading and writing.
public interface IHasTag // interface for reading. Maybe IReadTag
{
string Tag { get; }
}
public interface ITagChange // interface for writing. Maybe IWriteTag
{
string Tag { set; }
}
public class TaggableItem : IHasTag, ITagChange // implement both
{
public string Tag { get; set; }
}
// Tagging manager gets write access (ITagChange)
public class TaggingManager
{
private List<ITagChange> _taggedItems = new ();
public void TagItem(ITagChange item, string tag)
{
item.Tag = tag;
_taggedItems.Add(item);
}
public void ClearAllTags()
{
foreach (var item in _taggedItems)
{
item.Tag = "";
}
_taggedItems.Clear();
}
}
// Everyone else has read access only (IHasTag)
class SomeoneElse
{
private List<IHasTag> _taggedItems = new ();
public void DoSomething(IHasTag item)
{
_taggedItems.Add(item);
var tag = item.Tag; // do something with the tag
}
}
class Instantiation
{
public void Main()
{
TaggableItem x = new TaggableItem();
TaggingManager m = new TaggingManager();
m.TagItem(x, "name");
SomeoneElse s = new SomeoneElse();
s.DoSomething(x);
}
}

One possible option is to move the "getter" also to the TagManager. Then the manager is responsible for the tags. The object itself does not even need to know about the tags.
You still can restrict this by exchanging object with an interface.
public class TagManager
{
private Dictionary<object, string> _tagedItems = new Dictionary<object, string>();
public bool HasTag(object item)
{
return _tagedItems.ContainsKey(item);
}
public string GetTag(object item)
{
return _tagedItems[item];
}
public void SetTag(object item, string tag)
{
if(!HasTag(item))
{
_tagedItems.Add(item, tag);
}
else
{
_tagedItems[item] = tag;
}
}
}
I don't think that this is really a answer to the OP, but one possible solution for the underlying problem.

Add subtype objects to list of supertype, then return list of subtypes from list of supertypes

I have 3 interfaces.
public interface IItem
{
string Name { get; set; }
}
public interface IEquipable : IItem
{
void Equip();
}
public interface IConsumable : IItem
{
void Use();
}
IEquipable is implemented by the classes Helmet and Bow, and IConsumable is implemented by classes Potion and Food.
Then, I have a class with a property which contains a List of IItem, and proceed to add a few items of both IEquipable and IConsumable after instantiating it.
public class Character
{
public List<IItem> Items { get; private set; }
public Character()
{
this.Items = new List<IItem>();
}
public void AddItem(IItem item)
{
this.Items.Add(item);
}
}
Program.cs
...
Character char = new Character();
char.AddItem(new Potion());
char.AddItem(new Food());
char.AddItem(new Helmet());
char.AddItem(new Bow());
...
Is there a way I can get a List of all IEquipable members from the List of IItems, each AS IEquipable?
I want to do something like
...
List<IEquipable> equipmentList = //do something to char.Items and get all items of type IEquipable.
IEquipment equipment = equipmentList.First(...)
equipment.Equip();
...
I've tried using List<IEquipable> equipmentList = char.Items.OfType<IEquipable>().ToList() but the resulting list ends up empty.

I implemented (and fixed minor typos in) your code like this:
void Main()
{
Character character = new Character();
character.AddItem(new Potion());
character.AddItem(new Food());
character.AddItem(new Helmet());
character.AddItem(new Bow());
List<IEquipable> equipmentList = character.Items.OfType<IEquipable>().ToList();
}
public class Potion : IConsumable
{
public string Name { get; set; }
public void Use()
{
throw new NotImplementedException();
}
}
public class Food : IConsumable
{
public string Name { get; set; }
public void Use()
{
throw new NotImplementedException();
}
}
public class Helmet : IEquipable
{
public string Name { get; set; }
public void Equip()
{
throw new NotImplementedException();
}
}
public class Bow : IEquipable
{
public string Name { get; set; }
public void Equip()
{
throw new NotImplementedException();
}
}
public interface IItem
{
string Name { get; set; }
}
public interface IEquipable : IItem
{
void Equip();
}
public interface IConsumable : IItem
{
void Use();
}
public class Character
{
public List<IItem> Items { get; private set; }
public Character()
{
this.Items = new List<IItem>();
}
public void AddItem(IItem item)
{
this.Items.Add(item);
}
}
Your exact code (albeit char renamed to character) works perfectly fine. The equipmentList ends up with two elements. The issue you're seeing, i.e. "the resulting list ends up empty", is not reproducible with the code you've posted.

You can use the OfType method
Filters the elements of an IEnumerable based on a specified type.
Signature
public static IEnumerable<TResult> OfType<TResult> (this IEnumerable source)
Usage
var equipable = Character.Items.OfType<IEquipable>();
Or encapsulate it as a method in the instance or an extension method if you like

So it does work like I wanted. My actual code just had another issue and I'm a dummy for not actually posting that. So here it is, for future reference.
using System.Collections.Generic;
using RolePlayGame.Library.Items.Backstage;
using System.Linq;
using System.Text;
using System;
namespace RolePlayGame.Library.Characters.Backstage
{
public class Inventory
{
public List<IItem> StoredItems { get; private set; }
public List<EquippedItem> Gear { get; private set; }
public Inventory()
{
this.StoredItems = new List<IItem>();
this.Gear = new List<EquippedItem>();
}
public bool HasItem(string name)
{
return this.StoredItems.Exists(item => item.Name == name);
}
public bool HasItem(IItem item)
{
return this.StoredItems.Contains(item);
}
public void RemoveItem(string name)
{
int firstIndex = this.StoredItems.FindIndex(item => item.Name == name);
if (firstIndex != -1)
{
this.StoredItems.RemoveAt(firstIndex);
}
}
public void RemoveItem(IItem item)
{
int firstIndex = this.StoredItems.IndexOf(item);
if (firstIndex != -1)
{
this.StoredItems.RemoveAt(firstIndex);
}
}
public void AddItem(IItem item, int quantity)
{
for (int i = 0; i < quantity; i++)
{
this.StoredItems.Add(item);
}
}
public void AddItem(IItem item)
{
this.StoredItems.Add(item);
}
public bool CheckEquipmentSlot(EquipmentSlot slot)
{
return this.Gear.Exists(item => item.UsedSlots.Contains(slot));
}
public bool HasEquipment(IEquipment equipment)
{
return this.Gear.Exists(item => item.Item == equipment);
}
public void AddEquipment(IEquipment equipment)
{
IEquipment alreadyEquipped;
foreach (EquipmentSlot slot in equipment.SlotsUsed)
{
if (this.Gear.Exists(item => item.UsedSlots.Contains(slot)))
{
alreadyEquipped = this.Gear.Find(item => item.UsedSlots.Contains(slot)).Item;
this.RemoveEquipment(slot);
this.StoredItems.Add(alreadyEquipped);
}
}
EquippedItem newEquipment = new EquippedItem(equipment);
this.Gear.Add(newEquipment);
}
public void RemoveEquipment(EquipmentSlot slot)
{
this.Gear.RemoveAll(equipment => equipment.UsedSlots.Contains(slot));
}
public int GetAttributeBonusTotal(AttributeType attribute)
{
int bonusTotal = 0;
foreach (IEquipment item in this.StoredItems.OfType<IEquipment>().ToList())
{
bonusTotal += item.GetAttributeBonus(attribute);
}
return bonusTotal;
}
public int GetCarryWeight()
{
int totalWeight = 0;
foreach (IItem item in StoredItems)
{
totalWeight += item.Weight;
}
return totalWeight;
}
public string GearToString()
{
StringBuilder builder = new StringBuilder();
builder.Append(" Equipped Gear:");
foreach (EquippedItem equipment in this.Gear)
{
builder.Append($"\n {equipment.Item.Name}");
}
return builder.ToString();
}
public string ItemsToString()
{
StringBuilder builder = new StringBuilder();
builder.Append(" Inventory:");
foreach (IItem item in this.StoredItems.Distinct())
{
builder.Append($"\n {item.Name} x {this.StoredItems.FindAll(value => value == item).Count()}");
}
return builder.ToString();
}
public int GetDefenseRateAgainstTypeTotal(DamageType againstType)
{
int rate = 0;
List<IOutfit> outfits = this.Gear.Select(value => value.Item).OfType<IOutfit>().ToList();
foreach (IOutfit item in outfits)
{
rate += item.GetDefenseRateAgainstType(againstType);
}
return rate;
}
}
}
One of the last lines has the problem (now fixed). List<IOutfit> outfits = this.Gear.Select(value => value.Item).OfType<IOutfit>().ToList(); used to be List<IOutfit> outfits = this.Gear.OfType<IOutfit>().ToList();. But Gear is of type List<EquippedItem>, and EquippedItem is not an implementation of IItem.
Here is EquippedItem.cs
using RolePlayGame.Library.Items.Backstage;
using System.Collections.Generic;
namespace RolePlayGame.Library
{
public class EquippedItem
{
public List<EquipmentSlot> UsedSlots { get; set; }
public IEquipment Item { get; set; }
public EquippedItem(IEquipment equipment)
{
this.Item = equipment;
this.UsedSlots = equipment.SlotsUsed;
}
}
}
I needed to select the Item property from the items inside Gear as another list before doing the type filtering with .OfType<IOutfit>(). That's where .Select(value => value.Item) enters the stage.
So that's that. I'll learn to post actual code for future questions.

How do you remove items from several list boxes by removing one item associated with them all?

I want to remove Server1 from it's listbox, i'd want it to remove all the other items in the other listboxes associated with it as well. ("Server-Domain1" and all the "Server1-Domain1-CSR's"). Is there a way to do this?
To "bind" these list boxes i just used:
domainListBox.Items.Add((serverListBox.SelectedItem) + "-" + (this.domainTextbox.Text));
and
csrListBox.Items.Add((domainListBox.SelectedItem) + ("-CSR-1"));
csrListBox.Items.Add((domainListBox.SelectedItem) + ("-CSR-2"));
csrListBox.Items.Add((domainListBox.SelectedItem) + ("-CSR-3"));

If you choose your server from servers listbox, you can remove associated items like this (lets pretend there is some remove button, you selecting domain from listbox and clicking on remove button):
private void removeBtn_Click(object sender, EventArgs e)
{
List<string> items = csrListBox.Items.Cast<string>().ToList();
foreach (string item in csrListBox.Items)
{
Regex regex = new Regex(#"^" + domainListBox.SelectedItem + #"\w*");
Match match = regex.Match(item);
if (match.Success)
{
items.Remove(item);
}
}
csrListBox.DataSource = items;
}
Hope it helps.

Create a class that encapsulates the Server and it's details such as Domains and Csrs. Create a list of Servers and bind it to the first List Box. Then bind the other two List Boxes to the currently selected item of the first List Box. The end result may look like this:
serverListBox.ItemSource = Servers;
domainListBox.ItemSource = (serverListBox.SelectedItem as Server).Domains;
csrListBox.ItemSource = (serverListBox.SelectedItem as Server).Csrs;
This enables you to set the different List Boxes data without writing a lot of code that could make it unmaintainable.

Well, seeing your code, you just have to do something like this when you remove your server:
string server = serverListBox.SelectedItem as string;
serverListBox.Remove(server);
for (int i = domainListBox.Items.Count -1; i >-1; i--)
{
if (domainListBox.Items[i].ToString().StartsWith(server))
{
string domain = domainListBox.Items[i].ToString();
domainListBox.Items.RemoveAt(i);
for (int j = csrListBox.Items.Count-1; j > -1; j--)
{
if (csrListBox.Items[j].ToString().StartsWith(domain))
{
csrListBox.Items.RemoveAt(j);
}
}
}
}
Edit I have tested it now, this should work

a better option would be using observable pattern as
public class ObservableObject<T> : IList, IListSource
{
protected BindingSource src = null;
List<ListControl> Subscribers;
ObservableCollection<T> Data = new ObservableCollection<T>();
public bool IsReadOnly
{
get
{
return false;
}
}
public bool IsFixedSize
{
get
{
return false;
}
}
public int Count
{
get
{
return Data.Count;
}
}
public object SyncRoot
{
get
{
throw new NotImplementedException();
}
}
public bool IsSynchronized
{
get
{
throw new NotImplementedException();
}
}
public bool ContainsListCollection
{
get
{
return true;
}
}
object IList.this[int index]
{
get
{
return Data[index];
}
set
{
Data[index] = (T)value;
}
}
public T this[int index]
{
get
{
return Data[index];
}
set
{
Data[index] = value;
}
}
public ObservableObject()
{
Data.CollectionChanged += Domains_CollectionChanged;
Subscribers = new List<ListControl>();
src = new BindingSource();
src.DataSource = Data;
}
private void Domains_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{
src.ResetBindings(false);
}
public virtual void Subscribe(ListBox ctrl)
{
this.Subscribers.Add(ctrl);
//ctrl.DataBindings.Add(new Binding("SelectedValue", src, "Name",
// true, DataSourceUpdateMode.Never));
ctrl.DataSource = src;
}
public int Add(object value)
{
Data.Add((T)value);
return Data.Count - 1;
}
public bool Contains(object value)
{
return Data.Contains((T)value);
}
public void Clear()
{
Data.Clear();
}
public int IndexOf(object value)
{
return Data.IndexOf((T)value);
}
public void Insert(int index, object value)
{
Data.Insert(index, (T)value);
}
public void Remove(object value)
{
Data.Remove((T)value);
}
public void RemoveAt(int index)
{
Data.RemoveAt(index);
}
public void CopyTo(Array array, int index)
{
throw new NotImplementedException();
}
public IEnumerator GetEnumerator()
{
return Data.GetEnumerator();
}
public IList GetList()
{
return Data;
}
}
public class BaseModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private string _name;
public string Name
{
get { return _name; }
set
{
this._name = value;
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs("Name"));
}
}
}
}
public class CSR : BaseModel
{
public override string ToString()
{
return Name;
}
}
public class Domain : BaseModel
{
public ObservableObject<CSR> CSRs { get; set; }
public Domain()
{
CSRs = new ObservableObject<CSR>();
}
public override string ToString()
{
return Name;
}
}
public class Server : BaseModel
{
public ObservableObject<Domain> Domains { get; set; }
public Server()
{
Domains = new ObservableObject<Domain>();
}
public override string ToString()
{
return Name;
}
}
public class DataModel : BaseModel
{
public ObservableObject<Server> Servers
{
get; set;
}
public DataModel()
{
Servers = new ObservableObject<Server>();
}
public override string ToString()
{
return Name;
}
}
on Form
DataModel m = new DataModel();
public Form1()
{
...
m.Servers.Subscribe(listBox1);
}
private void listBox2_Click(object sender, EventArgs e)
{
if (listBox2.SelectedIndex >= 0)
{
m.Servers[listBox1.SelectedIndex].Domains[listBox2.SelectedIndex].CSRs.Subscribe(listBox3);
}
}
private void listBox1_Click(object sender, EventArgs e)
{
if (listBox1.SelectedIndex >= 0)
{
m.Servers[listBox1.SelectedIndex].Domains.Subscribe(listBox2);
}
}
you dont have to write code to remove items from forms in this perspective.removing object from model would do

What is NZEC error in C# and where it is in following code snippet

This is the first time I am getting NZEC error. I don't understand this error, I just found that it stands for "Non Zero Exit Code". But what does this means. When we get this error. I am getting this error on one of online coding challenge websites and not in Visual Studio.
I am real need of help. Please check following code snippet where I am getting this error and please suggest what I am doing wrong.
using System;
using System.Collections.Generic;
using System.Linq;
namespace PractiseConsoleApplication
{
internal class Program
{
private static void Main(string[] args)
{
//Get input
var stringInput = Console.ReadLine();
var numberOfRooms = Convert.ToInt32(Console.ReadLine());
var endOfInput = Convert.ToInt32(Console.ReadLine());
var customers = stringInput.ToArray();
var hotel = new Hotel(numberOfRooms);
foreach (var customerName in customers)
{
hotel.CheckInCheckoutCustomer(customerName);
}
Console.WriteLine(Convert.ToString(hotel.CustomersLeftWithoutStayingInHotel.Count));
}
}
internal class Hotel
{
public bool IsRoomAvailable { get; private set; }
public List<HotelRoom> Rooms { get; private set; }
public List<char> CustomersLeftWithoutStayingInHotel { get; private set; }
private Hotel()
{
Rooms = new List<HotelRoom>();
CustomersLeftWithoutStayingInHotel = new List<char>();
}
public Hotel(int numberOfRooms)
: this()
{
for (int i = 1; i <= numberOfRooms; i++)
{
Rooms.Add(new HotelRoom(i));
}
}
public void CheckInCheckoutCustomer(char customer)
{
if (CustomersLeftWithoutStayingInHotel.Any(f => f == customer))
{
return;
}
var existingCustomer = Rooms.FirstOrDefault(f => f.IsRoomAllocatedToCustomer && f.CustomerName == customer);
//Already room allocated to this customer
if (existingCustomer != null)
{
//checkout him
existingCustomer.CustomerCheckout();
}
else
{
//Get empty rooms
var emptyRoom = Rooms.FirstOrDefault(f => f.IsRoomAllocatedToCustomer == false);
if (emptyRoom != null)
{
emptyRoom.AllocateRoomToCustomer(customer);
}
else
{
CustomersLeftWithoutStayingInHotel.Add(customer);
}
}
}
}
internal class HotelRoom
{
public int RoomNumber { get; private set; }
public char? CustomerName { get; private set; }
public HotelRoom(int roomNumber)
{
RoomNumber = roomNumber;
CustomerName = null;
}
public bool IsRoomAllocatedToCustomer
{
get
{
return CustomerName.HasValue;
}
}
public void AllocateRoomToCustomer(char customerDetails)
{
CustomerName = customerDetails;
}
public void CustomerCheckout()
{
CustomerName = null;
}
}
internal class Customer
{
public char CustomerName { get; private set; }
public Customer(char name)
{
CustomerName = name;
}
}
}

as Tony Hopkinson says in the comments, main should return an int.
place this statement in the end of main method:
return 0;
this will exit with zero code(thus the Non Zero Exit Code error)

Nested object lists, last list not accessible?

In the code below I try to add the AttributeValueInfoEntity to the AttributeValueExportList, however it is not showing up as a property of the ArticleAttributeExportLarge object at the place where I put //largeExportList.AttributeExportList in the code.
Am I doing something wrong, or am I missing a important nesting rule in C#?
public partial class Export_Articles_Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
ArticleInfoEntity[] articleInfoList = ArticleInfoFactory.Instance.ListInfo(244);
List<ArticleExportLarge> list = new List<ArticleExportLarge>();
foreach (ArticleInfoEntity aie in articleInfoList)
{
ArticleExportLarge largeExportList = new ArticleExportLarge(aie);
largeExportList.AttributeExportList = new List<ArticleAttributeExportLarge>();
List<AttributeInfoEntity> attributeInfoList = AttributeInfoFactory.Instance.ListByArticle(aie.ArticleId);
foreach (AttributeInfoEntity attributeInfo in attributeInfoList)
{
largeExportList.AttributeExportList.Add(new ArticleAttributeExportLarge(attributeInfo));
List<AttributeValueInfoEntity> ArticleValueInfoList = AttributeValueInfoFactory.Instance.ListByArticleAndAttribute(aie.ArticleId, attributeInfo.AttributeId);
foreach (AttributeValueInfoEntity avie in ArticleValueInfoList)
{
//largeExportList.AttributeExportList
}
}
list.Add(largeExportList);
}
}
}
public class ArticleExportLarge
{
private ArticleInfoEntity articleInfo;
private List<ArticleAttributeExportLarge> attributeExportList;
public ArticleExportLarge(ArticleInfoEntity articleInfo)
{
this.articleInfo = articleInfo;
}
[XmlElement(ElementName = "attributeList")]
public List<ArticleAttributeExportLarge> AttributeExportList
{
get { return attributeExportList; }
set { attributeExportList = value; }
}
}
public class ArticleAttributeExportLarge
{
private AttributeInfoEntity attributeInfo;
private List<ArticleAttributeValueExportLarge> attributeValueExportList;
public ArticleAttributeExportLarge(AttributeInfoEntity attributeInfo)
{
this.attributeInfo = attributeInfo;
}
[XmlElement(ElementName = "attributeValueList")]
public List<ArticleAttributeValueExportLarge> AttributeValueExportList
{
get { return attributeValueExportList; }
set { attributeValueExportList = value; }
}
}
public class ArticleAttributeValueExportLarge
{
private AttributeValueInfoEntity attributeValueExportEntity;
public AttributeValueInfoEntity AttributeValueExportEntity
{
get { return attributeValueExportEntity; }
set { this.attributeValueExportEntity = value; }
}
}

I found my error. I need to iterate through the secondary list largeExportList.AttributeExportList if I want to access the objects in that list.