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Generate a strongly-typed proxy that can track changes on property names not values when one property is set to another

Setup:
public class Data
{
public int A { get; set; }
public int B { get; set; }
}
public class Runner
{
public static void Run(Data data)
{
data.A = data.B;
data.A = 1;
}
}
class Program
{
static void Main(string[] args)
{
var data = new Data() { A = 1, B = 2 };
Runner.Run(data);
}
}
Problem: I need to implement change tracking here for property names not values. Inside Runner.Run on the first line data.A = data.B I need to record somehow that "A" was set to "B" (literally property names) and then on the next line data.A = 1 I need to record that "A" was set to constant and say forget about it.
Constrains:
When setting one property to another (e.g. A = B) that needs to be recorded
When setting property to anything else (e.g. A = 1 or A = B * 2) this change needs to be forgotten (e.g. remember A only)
Suppose this is the tracker contract being used:
void RecordChange(string setterName, string getterName);
void UnTrackChange(string setterName);
Question:
I would like to somehow proxy the Data class so it still can be used in the interface code (e.g. Runner - is a whole bunch of a business logic code that uses Data) INCLUDING strong-typing and it can track it's changes without modifying the code (e.g. there is lots of places like 'data.A = data.B').
Is there any way to do it without resorting to I guess some magic involving IL generation?
Already investigated/tried:
PostSharp interceptors/Castle.DynamicProxy with interceptors - these alone cannot help. The most I can get out of it is to have a value of data.B inside setter interceptor but not nameof(data.B).
Compiler services - haven't found anything suitable here - getting the name of caller doesn't really help.
Runtine code generation - smth like proxy inherited from DynamicObject or using Relfection.Emit (TypeBuilder probably) - I lose typings.
Current solution:
Use the Tracker implementation of the abovementioned contract and pass it around into every function down the road. Then instead of writing data.A = data.B use method tracker.SetFrom(x => x.A, x => x.B) - tracker holds a Data instance and so this works. BUT in a real codebase it is easy to miss something and it just makes it way less readable.

It is the closest the solution I've come up with. It isn't perfect as I still need to modify all the contracts/methods in the client code to use a new data model but at least all the logic stays the same.
So I'm open for other answers.
Here's the renewed Data model:
public readonly struct NamedProperty<TValue>
{
public NamedProperty(string name, TValue value)
{
Name = name;
Value = value;
}
public string Name { get; }
public TValue Value { get; }
public static implicit operator TValue (NamedProperty<TValue> obj)
=> obj.Value;
public static implicit operator NamedProperty<TValue>(TValue value)
=> new NamedProperty<TValue>(null, value);
}
public interface ISelfTracker<T>
where T : class, ISelfTracker<T>
{
Tracker<T> Tracker { get; set; }
}
public class NamedData : ISelfTracker<NamedData>
{
public virtual NamedProperty<int> A { get; set; }
public virtual NamedProperty<int> B { get; set; }
public Tracker<NamedData> Tracker { get; set; }
}
Basically I've copy-pasted the original Data model but changed all its properties to be aware of their names.
Then the tracker itself:
public class Tracker<T>
where T : class, ISelfTracker<T>
{
public T Instance { get; }
public T Proxy { get; }
public Tracker(T instance)
{
Instance = instance;
Proxy = new ProxyGenerator().CreateClassProxyWithTarget<T>(Instance, new TrackingNamedProxyInterceptor<T>(this));
Proxy.Tracker = this;
}
public void RecordChange(string setterName, string getterName)
{
}
public void UnTrackChange(string setterName)
{
}
}
The interceptor for Castle.DynamicProxy:
public class TrackingNamedProxyInterceptor<T> : IInterceptor
where T : class, ISelfTracker<T>
{
private const string SetterPrefix = "set_";
private const string GetterPrefix = "get_";
private readonly Tracker<T> _tracker;
public TrackingNamedProxyInterceptor(Tracker<T> proxy)
{
_tracker = proxy;
}
public void Intercept(IInvocation invocation)
{
if (IsSetMethod(invocation.Method))
{
string propertyName = GetPropertyName(invocation.Method);
dynamic value = invocation.Arguments[0];
var propertyType = value.GetType();
if (IsOfGenericType(propertyType, typeof(NamedProperty<>)))
{
if (value.Name == null)
{
_tracker.UnTrackChange(propertyName);
}
else
{
_tracker.RecordChange(propertyName, value.Name);
}
var args = new[] { propertyName, value.Value };
invocation.Arguments[0] = Activator.CreateInstance(propertyType, args);
}
}
invocation.Proceed();
}
private string GetPropertyName(MethodInfo method)
=> method.Name.Replace(SetterPrefix, string.Empty).Replace(GetterPrefix, string.Empty);
private bool IsSetMethod(MethodInfo method)
=> method.IsSpecialName && method.Name.StartsWith(SetterPrefix);
private bool IsOfGenericType(Type type, Type openGenericType)
=> type.IsGenericType && type.GetGenericTypeDefinition() == openGenericType;
}
And the modified entry point:
static void Main(string[] args)
{
var data = new Data() { A = 1, B = 2 };
NamedData namedData = Map(data);
var proxy = new Tracker<NamedData>(namedData).Proxy;
Runner.Run(proxy);
Console.ReadLine();
}
The Map() function actually maps Data to NamedData filling in property names.

Cannot implicitly convert A<B> to A<C<D>> where B inherit from C<D>

I'm building a sort of library to perform text replacement in a document based on some rule. We built a POC and now I'm trying to create a library as generic as possible.
I have just one problem with inheritance:
This is the simplified representation of the classes/interfaces I'm dealing with:
public interface IRule {}
public interface IReplaceRule<T> : IRule
{
T ReplaceValue { get; set; }
}
public class CachedRules<T> where T : IReplaceRule<object>
{
#region Props
public T RuleTemplate { get; set; }
public IDictionary<string, T> RuleList { get; private set; } = null;
#endregion
public void SetRuleList(IDictionary<string, T> ruleList) { ... }
public bool ContainsRuleByKey(string key) { ... }
public bool TryGetRuleValueByKey(string key, out T rule) { ... }
}
public class SingleRowRule : IReplaceRule<string> { ... }
I also have a class which is like a repository of rules, and inside it I can add as many CachedRules as I need:
public class RulesStorage : AbstractRulesStorage
{
private CachedRules<SingleRowRule> singleRowRules;
public RulesStorage() { ... }
// Bunch of methods not useful for this question
// Here I need to return a list of ChachedRule, but just ofr testing I tried to return only one
public CachedRules<IReplaceRule<object>> GetCachedReplaceRules()
{
return singleRowRules;
}
}
Inside this class I need a method to return all the CachedRules declared in the RulesStorage:
Unfortunately the RulesStorage.GetCachedReplaceRules method give me this error:
Cannot implicitly convert type TestLib.Model.CachedRules<TestLib.Rules.SingleRowRule> to TestLib.Model.CachedRules<TestLib.Abstractions.IReplaceRule<object>
I really don't like the fact that I had to put <object> since IReplaceRule requires a generic and also I'm stuck because I don't know how to return this list of CachedRules without getting this compilation error.
Do you have some idea? Do I have to organize the code differently in your opinion?
Hope I've made myself clear and thanks in advance!

Instead of doing IReplaceRule<object> you can do it the way IEnumerable<T> inherits from IEnumerable. With that minor tweak in place, I create an implicit converter to go from T to IReplaceRule and the constraint in place now ensures I can actually do this safely.
I'm assuming you have a reason to have private CachedRules<SingleRowRule> singleRowRules; and can't just using private CachedRules<IReplaceRule> singleRowRules; which would remove the need for this extra conversion hop.
Code:
public interface IReplaceRule : IRule { object ReplaceValue { get; set; } }
public interface IReplaceRule<T> : IReplaceRule { new T ReplaceValue { get; set; } }
public class CachedRules<T> where T : IReplaceRule
{
public IDictionary<string, T> RuleList { get; private set; } = new Dictionary<string, T>();
//The key ingredient for a nice experience instead of just doing this in the method
public static implicit operator CachedRules<IReplaceRule>(CachedRules<T> rules)
=> new CachedRules<IReplaceRule> { RuleList = rules.RuleList.ToDictionary(x => x.Key, x => x.Value as IReplaceRule) };
}
public class SingleRowRule : IReplaceRule<string>
{
public string ReplaceValue { get; set; }
object IReplaceRule.ReplaceValue { get => ReplaceValue; set => ReplaceValue = value as string; }
}
public class RulesStorage
{
private CachedRules<SingleRowRule> singleRowRules = new CachedRules<UserQuery.SingleRowRule>();
//FIXME: just for testing purposes
public RulesStorage() => singleRowRules.RuleList.Add("Hello", new SingleRowRule { ReplaceValue = "World" });
// Here I need to return a list of ChachedRule, but just ofr testing I tried to return only one
public CachedRules<IReplaceRule> GetCachedReplaceRules() => singleRowRules;
}

Inherit in generic classes C#

My brain is gonna to explode. :) So I would like to get help from you.
Please, think about my question like about just programmer puzzle. (Actually. perhaps it is very easy question for you, but not for me.)
It is needed to create array of objects. For example List where T is class. (I will describe Class T below). Also it is needed create “container” that will contain this array and some methods for work with this array. For example Add(), Remove(int IndexToRemove).
Class T must have field "Container", this way each elements of our array would be able to know where is it contained and has access its container's fields and methods. Notice, that in this case Class T should have type parameter. Indeed, it is not known beforehand which container's type is used.
Let us denote this class container as A and class element (class T) as AUnit.
Code:
class Program
{
static void Main(string[] args)
{
A a = new A();
a.Add();
a.Units[0].SomeField +=100;
Console.ReadKey();
}
}
class A
{
public List<AUnit> Units;
public A()//ctor
{
Units = new List<AUnit>();
}
public void Add()
{
this.Units.Add(new AUnit(this));
}
}
class AUnit
{
public int SomeField;
public A Container;
public string Name { get; private set; }
public AUnit(A container)
{
this.SomeField = 43;
this.Container = container;
this.Name = "Default";
}
}
Public fields should be protected or private of course, but let think about this later.
You can ask “why we create public A Container field in AUnit”? We create field public string Name{get;private set;} (actually property but nevermind). And also we would like to be able to change value of this field for example method [Class AUnit] public bool Rename(string newName)();. The main idea of this method is changing Name field only that case if no one element in array (public List Units; ) has the same name like newName. But to achieve this, Rename method has to have access to all names that is currently used. And that is why we need Container field.
Code of extended version AUnit
class AUnit
{
public int SomeField;
public A Container;
public string Name { get; private set; }
public AUnit(A container)
{
this.SomeField = 43;
this.Container = container;
this.Name = "Default";
}
public bool Rename(String newName)
{
Boolean res = true;
foreach (AUnit unt in this.Container.Units)
{
if (unt.Name == newName)
{
res = false;
break;
}
}
if (res) this.Name = String.Copy(newName);
return res;
}
}
Ok. If you still read it let's continue. Now we need to create Class B and class BUnit which will be very similar like Class A and Class Aunit. And finally the main question of this puzzle is HOW WE CAN DO IT? Of course, I can CopyPaste and bit modify A and AUnit and create this code.
class B
{
public List<BUnit> Units; //Only Type Changing
public B()//ctor Name changing...
{
Units = new List<BUnit>();//Only Type Changing
}
public void Add()
{
this.Units.Add(new BUnit(this));//Only Type Changing
}
}
class BUnit
{
public int SomeField;
public B Container;//Only Type Changing
public string Name { get; private set; }
public A a; //NEW FIELD IS ADDED (just one)
public BUnit(B container) //Ctor Name and arguments type changing
{
this.SomeField = 43;
this.Container = container;
this.Name = "Default";
this.a=new A(); //New ROW (just one)
}
public bool Rename(String newName)
{
Boolean res = true;
foreach (BUnit unt in this.Container.Units) //Only Type Changing
{
if (unt.Name == newName)
{
res = false;
break;
}
}
if (res) this.Name = String.Copy(newName);
return res;
}
}
And I can to use this classes this way.
static void Main(string[] args)
{
B b = new B();
b.Add();
b.Units[0].a.Add();
b.Units[0].a.Units[0].SomeField += 100;
bool res= b.Units[0].a.Units[0].Rename("1");
res = b.Units[0].a.Units[0].Rename("1");
Console.ReadKey();
}
This construction is can be used to create “non-homogeneous trees”.
Help, I need somebody help, just no anybody…. [The Beatles]
I created B and BUnit using CopyPaste.
But how it can be done using “macro-definitions” or “Generic”, inherit or anything else in elegant style? (C# language)
I think that there is no reason to describe all my unsuccessful attempts and subquestions. Already topic is too long. : )
Thanks a lot if you still read it and understand what I would like to ask.

You need to implement a base type, lets call it UnitBase, with all common functionality. I'd structure your code the following way:
Create an interface for your container, this way you can change implementation to more performant solutions without modifying the elements you will be adding to the container.
public interface IContainer
{
Q Add<Q>() where Q : UnitBase, new();
IEnumerable<UnitBase> Units { get; }
}
Following the idea stated in 1, why not make the search logic belong to the container? It makes much more sense, as it will mostly depend on how the container is implemented:
public interface IContainer
{
Q Add<Q>() where Q : UnitBase, new();
IEnumerable<UnitBase> Units { get; }
bool Contains(string name);
}
A specific implementation of IContainer could be the following:
public class Container : IContainer
{
public Container()
{
list = new List<UnitBase>();
}
private List<UnitBase> list;
public Q Add<Q>() where Q: UnitBase, new()
{
var newItem = Activator.CreateInstance<Q>();
newItem.SetContainer(this);
list.Add(newItem);
return newItem;
}
public IEnumerable<UnitBase> Units => list.Select(i => i);
public bool Contains(string name) =>
Units.Any(unit => unit.Name == name);
}
Create a base class for your AUnit and BUnit types condensing all common functionality:
public abstract class UnitBase
{
protected UnitBase()
{
}
public IContainer Container { get; private set; }
public int SomeField;
public string Name { get; private set; }
public void SetContainer(IContainer container)
{
Container = container;
}
public bool Rename(String newName)
{
if (Container.Contains(newName))
return false;
this.Name = newName; //No need to use String.Copy
return true;
}
}
Implement your concrete types:
public class BUnit : UnitBase
{
public int SpecificBProperty { get; private set; }
public BUnit()
{
}
}
Shortcomings of this approach? Well, the container must be of type <UnitBase>, I've removed the generic type because it really wasn't doing much in this particular case as it would be invariant in the generic type.
Also, keep in mind that nothing in the type system avoids the following:
myContainer.Add<BUnit>();
myContainer.Add<AUnit>();
If having two different types in the same container is not an option then this whole set up kind of crumbles down. This issue was present in the previous solution too so its not something new, I simply forgot to point it out.

InBetween , I am very thankful to you for your advices. Actually I can't say that I understood your answer in full, but using your ideas I have done what I want.
Looks like my variant works well. However I would like to hear your (and everyone) opinions about code described below. The main goal of this structure is creating non-homogeneous trees. So could you estimate it from this side.
First of all. We need to create interfaces for both classes. We describe there all "cross-used" functions.
public interface IUnit<T>
{
string Name { get;}
void SetContainer(T t);
bool Rename(String newName);
}
public interface IContainer
{
bool IsNameBusy(String newName);
int Count { get; }
}
Next. Create Base for Unit Classes for future inheritance. We will use in this inheritors methods from Container Base so we need generic properties and IUnit interface.
class UnitBase<T> : IUnit<T> where T : IContainer
Unfortunately I don't know yet how to solve the problem with Constructor parameters. That is why I use method
SetContainer(T container).
Code:UnitBase
class UnitBase<T> : IUnit<T> where T : IContainer
{
protected T Container;
public string Name { get; private set; }
public UnitBase()
{
this.Name = "Default";
}
public void SetContainer(T container)
{
this.Container = container;
}
public bool Rename(String newName)
{
bool res = Container.IsNameBusy(newName);
if (!res) this.Name = String.Copy(newName);
return !res;
}
}
Next. Create ContainerBase
ContainerBase should:
1) has IContainer interface.
2)has information about what it will contain:
... where U : IUnit<C>, new()
3)and .... has information about what itself is. This information we need to pass as parameter to SetContainer() method.
Code ContainerBase:
class ContainerBase<U, C> : IContainer //U - Unit Class. C-Container Class
where U : IUnit<C>, new()
where C : ContainerBase<U, C>
{
protected List<U> Units;
public U this[int index] { get { return Units[index]; } }
public ContainerBase()//ctor
{
this.Units = new List<U>();
}
public void Add()
{
this.Units.Add(new U());
this.Units.Last().SetContainer(((C)this));//may be a bit strange but actualy this will have the same type as <C>
}
public bool IsNameBusy(String newName)
{
bool res = false;
foreach (var unt in this.Units)
{
if (unt.Name == newName)
{
res = true;
break;
}
}
return res;
}
public int Count { get { return this.Units.Count; } }
}
Cast ((TContainer)(this)) may be is a bit strange. But using ContainerBase we always should use NewInheritorContainer. So this cast is just do nothing…looks like...
Finally. This classes can be used like in this example.
class SheetContainer : ContainerBase<SheetUnit,SheetContainer> {public SheetContainer(){}}
class SheetUnit : UnitBase<SheetContainer>
{
public CellContainer Cells;
public PictureContainer Pictures;
public SheetUnit()
{
this.Cells = new CellContainer();
this.Pictures = new PictureContainer();
}
}
class CellContainer : ContainerBase<CellUnit, CellContainer> { public CellContainer() { } }
class CellUnit : UnitBase<CellContainer>
{
public string ValuePr;//Private Field
private const string ValuePrDefault = "Default";
public string Value//Property for Value
{
//All below are Just For Example.
get
{
return this.ValuePr;
}
set
{
if (String.IsNullOrEmpty(value))
{
this.ValuePr = ValuePrDefault;
}
else
{
this.ValuePr = String.Copy(value);
}
}
}
public CellUnit()
{
this.ValuePr = ValuePrDefault;
}
}
class PictureContainer : ContainerBase<PictureUnit, PictureContainer> { public PictureContainer() { } }
class PictureUnit : UnitBase<PictureContainer>
{
public int[,] Pixels{get;private set;}
public PictureUnit()
{
this.Pixels=new int[,]{{10,20,30},{11,12,13}};
}
public int GetSizeX()
{
return this.Pixels.GetLength(1);
}
public int GetSizeY()
{
return this.Pixels.GetLength(0);
}
public bool LoadFromFile(string path)
{
return false;
}
}
static void Main(string[] args)
{
SheetContainer Sheets = new SheetContainer();
Sheets.Add();
Sheets.Add();
Sheets.Add();
Sheets[0].Pictures.Add();
Sheets[1].Cells.Add();
Sheets[2].Pictures.Add();
Sheets[2].Cells.Add();
Sheets[2].Cells[0].Value = "FirstTest";
bool res= Sheets[0].Rename("First");//res=true
res=Sheets[2].Rename("First");//res =false
int res2 = Sheets.Count;
res2 = Sheets[2].Pictures[0].Pixels[1, 2];//13
res2 = Sheets[2].Pictures.Count;//1
res2 = Sheets[1].Pictures.Count;//0
res2 = Sheets[0].Pictures[0].GetSizeX();//3
Console.ReadKey();
}
Looks like it works like I want. But I didn’t test it full.
Let me say Thank you again, InBetween.

using Explicit Interface Implementation

I am trying to change the property type in interface implementation class using explicit interface implementation.
interface ISample
{
object Value { get; set; }
}
class SampleA : ISample
{
SomeClass1 Value { get; set; }
object ISample.Value
{
get { return this.Value; }
set { this.Value = (SomeClass1)value; }
}
}
class SampleB : ISample
{
SomeClass2 Value { get; set; }
object ISample.Value
{
get { return this.Value; }
set { this.Value = (SomeClass2)value; }
}
}
class SomeClass1
{
string s1;
string s2;
}
But when I need to pass in interface obj in a function, I cant access the objects of SomeClass1 or SomeClass2.
For eg:
public void MethodA(ISample sample)
{
string str = sample.Value.s1;//doesnt work.How can I access s1 using ISample??
}
I don't know if this is understandable, but I cant seem to get an easier way to explain this. Is there a way to access the properties of SomeClass1 using interface ISample?
Thanks

That is because you've received the object as the interface, so it doesn't know about the class's new property type. You would need to:
public void MethodA(ISample sample)
{
if (sample is SampleA)
{
string str = ((SampleA)sample).Value.s1;
}
}
A better solution might be to use the visitor pattern - which would have implementations for handling the different ISample's.

Refactoring a list of objects to implement a business rule

I need to refactor the following class:
public interface IEmployee
{
int VacationWeeks { get; }
int YearsWithCompany { set; get; }
double Salary { set; get; }
}
public class Employee : IEmployee
{
private readonly int vacationWeeks;
public Employee(int vacationWeeks)
{
this.vacationWeeks = vacationWeeks;
}
public int VacationWeeks
{
get { return vacationWeeks; }
}
public int YearsWithCompany { set; get; }
public double Salary { set; get; }
}
I need to make sure that VacationWeeks depends only on YearsWithCompany, and I am loading the mapping from the database. So far I have come up with this:
public class EmployeeNew : IEmployee
{
private Dictionary<int,int> vacationWeeksTable;
public EmployeeNew(Dictionary<int, int> vacationWeeksTable)
{
this.vacationWeeksTable = vacationWeeksTable;
}
public int VacationWeeks
{
get { return vacationWeeksTable[YearsWithCompany]; }
}
public int YearsWithCompany { set; get; }
public double Salary { set; get; }
}
This class implements what I want, but it still has one vulnerability: different instances of EmployeeNew in the same collection may have been created with different instances of vacationWeeksTable.
All instances of EmployeeNew in the same collection must refer to the same vacationWeeksTable.
The application I am refactoring uses lots of List all over the system, and we need to be able to modify YearsWithCompany and Salary, yet to guarantee that only one vacationWeeksTable is used per List. These lists are iterated several times; its elements are modified in each iteration.
Here is my imperfect solution. Suggestions are welcome:
// this class does two things, which I do not like
public class EmployeeList : IEnumerable<IEmployee>, IEmployee
{
private Dictionary<int, int> vacationWeeksTable;
private List<EmployeeSpecificData> employees;
private int currentIndex;
private EmployeeSpecificData CurrentEmployee
{
get { return employees[currentIndex]; }
}
public IEnumerator<IEmployee> GetEnumerator()
{
for (currentIndex = 0; currentIndex < employees.Count; currentIndex++)
{
yield return this;
}
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
public int VacationWeeks
{
get { return vacationWeeksTable[YearsWithCompany]; }
}
// this is ugly repetitive code I don't like
public int YearsWithCompany
{
get { return CurrentEmployee.YearsWithCompany; }
set { CurrentEmployee.YearsWithCompany = value; }
}
// this is ugly repetitive code I don't like
public double Salary
{
get { return CurrentEmployee.Salary; }
set { CurrentEmployee.Salary = value; }
}
}

I use the following to create and init some of the classes that need default and shared behaviour. Maybe if you can refactor it will help:
It is some form of the Factory and FlyWeight patterns combined (the flyweight part can be removed in your scenario), which in addition has a concept of class Type shared handlers.
I simplified and removed some stuff that you wont need but there is more to remove, I added comments.
Usage would be: (app init)
Dictionary<int,int> vacationWeeksTable = new Dictionary<int,int>();
// fill the table
Factory<Employee>.Init(vacationWeeksTable);
The whenever you create a Employee class:
// remove grouping in the factory class to remove this null
Employee em = Factory<Employee>.Create(null);
It takes only a WeakReference to the classes so you don't have to worry about GC.
Each employee will have the shared vacationWeeksTable setup on creation, without the possibility to change it after from outside if not using the factory class.
You could change the vacation table for all running instances of Employee at any moment in the runtime of the app with:
// this will call the method registered for SetInitialdata on all instances of Employee classes.
// again remove grouping to remove that null
Factory<Employee>.Call(EventHandlerTypes.SetInitialData, null, vacTable);
Sample implementation of Employee:
class Employee : IBaseClass
{
private Dictionary<int, int> vacationWeeksTable;
public virtual void RegisterSharedHandlers(int? group, Action<IKey, int?, EventHandlerTypes, Action<object, SharedEventArgs>> register)
{
group = 0; // disable different groups
register(new Key<Employee, int>(0), group, EventHandlerTypes.SetInitialData, SetVacationWeeksTable);
}
public virtual void RegisterSharedData(Action<IKey, object> regData)
{
// remove this from factory and interface, you probably dont need it
// I have been using it as a FlyWeight data store for classes.
}
private void SetVacationWeeksTable(object sender, SharedEventArgs e)
{
vacationWeeksTable = e.GetData<Dictionary<int, int>>();
}
}
Code pattern Implementation:
IBaseClass : interface that each of my classes that are creatable through a factory implement
public enum EventHandlerTypes
{
SetInitialData // you can add additional shared handlers here and Factory<C>.Call - it.
}
public class SharedEventArgs : EventArgs
{
private object data;
public SharedEventArgs(object data)
{
this.data = data;
}
public T GetData<T>()
{
return (T)data;
}
}
public interface IBaseClass
{
void RegisterSharedHandlers(int? group, Action<IKey, int?, EventHandlerTypes, Action<object, SharedEventArgs>> regEvent);
void RegisterSharedData(Action<IKey, object> regData);
}
Utility generic classes:
public interface IKey
{
Type GetKeyType();
V GetValue<V>();
}
public class Key<T, V> : IKey
{
public V ID { get; set; }
public Key(V id)
{
ID = id;
}
public Type GetKeyType()
{
return typeof(T);
}
public Tp GetValue<Tp>()
{
return (Tp)(object)ID;
}
}
public class Triple<T, V, Z>
{
public T First { get; set; }
public V Second { get; set; }
public Z Third { get; set; }
public Triple(T first, V second, Z third)
{
First = first;
Second = second;
Third = third;
}
}
Factory class with slight modification to handle your scenario:
public static class Factory<C> where C : IBaseClass, new()
{
private static object initialData;
private static Dictionary<IKey, Triple<EventHandlerTypes, int, WeakReference>> handlers = new Dictionary<IKey, Triple<EventHandlerTypes, int, WeakReference>>();
private static Dictionary<IKey, object> data = new Dictionary<IKey, object>();
static Factory()
{
C newClass = new C();
newClass.RegisterSharedData(registerSharedData);
}
public static void Init<IT>(IT initData)
{
initialData = initData;
}
public static Dt[] GetData<Dt>()
{
var dataList = from d in data where d.Key.GetKeyType() == typeof(Dt) select d.Value;
return dataList.Cast<Dt>().ToArray();
}
private static void registerSharedData(IKey key, object value)
{
data.Add(key, value);
}
public static C Create(int? group)
{
C newClass = new C();
newClass.RegisterSharedHandlers(group, registerSharedHandlers);
// this is a bit bad here since it will call it on all instances
// it would be better if you can call this from outside after creating all the classes
Factory<C>.Call(EventHandlerTypes.SetInitialData, null, initialData);
return newClass;
}
private static void registerSharedHandlers(IKey subscriber, int? group, EventHandlerTypes type, Action<object, SharedEventArgs> handler)
{
handlers.Add(subscriber, new Triple<EventHandlerTypes, int, WeakReference>(type, group ?? -1, new WeakReference(handler)));
}
public static void Call<N>(EventHandlerTypes type, int? group, N data)
{
Call<N>(null, type, group, data);
}
public static void Call<N>(object sender, EventHandlerTypes type, int? group, N data)
{
lock (handlers)
{
var invalid = from h in handlers where h.Value.Third.Target == null select h.Key;
// delete expired references
foreach (var inv in invalid.ToList()) handlers.Remove(inv);
var events = from h in handlers where h.Value.First == type && (!#group.HasValue || h.Value.Second == (int)#group) select h.Value.Third;
foreach (var ev in events.ToList())
{
// call the handler
((Action<object, SharedEventArgs>)ev.Target)(sender, arg);
}
}
}
}

Make a class which contains a Dictionary. Creating or getting instance of this new class will load the dictionary in a consistent way. Then your BOs can take an instance of the class, thus ensuring they're all using the same data (because the class containingthe list knows how to load itself with the proper set of data).