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how to call Inner Class in C#

i am trying to set inner class value from outer class using event handler
here the line for passing the value , PaymentMode is Event
public event PaymentModeEven PaymentMode;
PaymentMode(this,new PaymentModeEvenArgs() { paymentSuccess = true });
Inner Class
public class PaymentModeEvenArgs: EventArgs
{
private bool PaymentSuccess;
public bool paymentSuccess
{
get { return paymentSuccess; }
set
{
paymentSuccess = value;
}
}
}
Program get stuck and stopped

You have a stack overflow exception. Consider your property:
public bool paymentSuccess
{
get { return paymentSuccess; }
set
{
paymentSuccess = value;
}
}
When you get or set paymentSuccess, what does it do internally? It gets or sets paymentSuccess. Which, internally, gets or sets paymentSuccess. Which, internally... You get the idea.
It looks like you meant to swap the casing between the field and the property:
private bool paymentSuccess;
public bool PaymentSuccess
{
get { return paymentSuccess; }
set
{
paymentSuccess = value;
}
}
Or, even better, just use an auto-implemented property so you only have to make one named member:
public bool PaymentSuccess { get; set; }

How do I detect changes in nested properties?

In C#, I have a suffiently complex Model. I already have a WPF Client to manipulate that model. I'm using MVVM. All objects in that model support INotifyPropertyChanged and all properties that are collections support INotifyCollectionChanged.
Take this as a simplied example:
using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
namespace CollectionTest1
{
public class PropertyChangedSupport : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void FirePropertyChange([System.Runtime.CompilerServices.CallerMemberName] string propertyName = "")
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
public class Company : PropertyChangedSupport
{
private string name;
public String Name { get { return name; } set { name = value; FirePropertyChange(); } }
public ObservableCollection<Employee> Employees { get; } = new ObservableCollection<Employee>();
}
public class Employee : PropertyChangedSupport
{
private string name;
public String Name { get { return name; } set { name = value; FirePropertyChange(); } }
public ObservableCollection<PresentTimespan> PresentTimespans { get; } = new ObservableCollection<PresentTimespan>();
public Boolean IsPresentAt(DateTime t)
{
foreach (PresentTimespan pt in PresentTimespans)
{
if (pt.Start.CompareTo(t) <= 0 && pt.Finish.CompareTo(t) >= 0) return true;
}
return false;
}
}
public class PresentTimespan : PropertyChangedSupport
{
private string comment;
public String Comment { get { return comment; } set { comment = value; FirePropertyChange(); } }
private DateTime start;
public DateTime Start { get { return start; } set { start = value; FirePropertyChange(); } }
private DateTime finish;
public DateTime Finish { get { return finish; } set { finish = value; FirePropertyChange(); } }
}
public class CompanyStatusView : PropertyChangedSupport
{
private DateTime currentTime;
public DateTime CurrentTime { get { return currentTime; } set { currentTime = value; FirePropertyChange(); } }
private Company currentCompany;
public Company CurrentCompany { get { return currentCompany; } set { currentCompany = value; FirePropertyChange(); } }
public ObservableCollection<Employee> PresentEmployees { get; } = new ObservableCollection<Employee>();
public CompanyStatusView()
{
UpdatePresentEmployees();
}
private void UpdatePresentEmployees()
{
PresentEmployees.Clear();
foreach (Employee e in CurrentCompany.Employees) {
if (e.IsPresentAt(currentTime)) PresentEmployees.Add(e);
}
}
}
}
I'd like to have UpdatePresentEmployees called whenever there are changes in:
Collection Company.Employees.PresentTimespans
Property Company.Employees.PresentTimespans.Start
Property Company.Employees.PresentTimespans.Finish
Collection Company.Employees
Property CurrentTime
Property CurrentCompany
So it's basically any property or collection read by UpdatePresentEmployees.
My best solution so far included registering a lot of event handlers to all the objects mentioned above. That included to have a couple of Dictionary instances to track which added objects I have to subscribe to and especially which I have to unsubscribe from.
The most difficult and annoying part was to subscribe to all the PresentTimespan objects to listen for property changes and all the PresentTimespans collections of Employee to listen for collection changes.
My guess is that there has to be a better way to do this.
After all, in JFace (Java) there is a very interesting solution that uses ObservableTracker. So there you'd only provide the code for UpdatePresentEmployees and ObservableTracker tracks which objects have been read and automatically makes you listen for changes in any of these and also correctly unsubscribes from irrelevant objects. So there are better approaches to this problem in general. What is C# offering? Can it do better than my best solution I mentioned above? Can I avoid some of the boilerplate code? Can it be done with .net provided classes or do I need some additional classes/libraries?
Thanks for your kind help and advice in advance!

You could use BindingList instead of ObservableCollection and attach to the the ListChanged Event. But keep in mind that BindingList has some disadvantages like not being very fast. For further information this could be interesting: difference between ObservableCollection and BindingList
If you dont wanna use BindingList you have to wire your items with events.

As pointed out by Nikhil Agrawal, Rx or ReactiveUI is a good framework for my purpose. So I consider that to be a solution.

how to implement selective property-visibility in c#?

Can we make a property of a class visible to public , but can only be modified by some specific classes?
for example,
// this is the property holder
public class Child
{
public bool IsBeaten { get; set;}
}
// this is the modifier which can set the property of Child instance
public class Father
{
public void BeatChild(Child c)
{
c.IsBeaten = true; // should be no exception
}
}
// this is the observer which can get the property but cannot set.
public class Cat
{
// I want this method always return false.
public bool TryBeatChild(Child c)
{
try
{
c.IsBeaten = true;
return true;
}
catch (Exception)
{
return false;
}
}
// shoud be ok
public void WatchChild(Child c)
{
if( c.IsBeaten )
{
this.Laugh();
}
}
private void Laugh(){}
}
Child is a data class,
Parent is a class that can modify data,
Cat is a class that can only read data.
Is there any way to implement such access control using Property in C#?

Rather than exposing the inner state of the Child class you could provide a method instead:
class Child {
public bool IsBeaten { get; private set; }
public void Beat(Father beater) {
IsBeaten = true;
}
}
class Father {
public void BeatChild(Child child) {
child.Beat(this);
}
}
Then the cat can't beat your child:
class Cat {
public void BeatChild(Child child) {
child.Beat(this); // Does not compile!
}
}
If other people need to be able to beat the child, define an interface they can implement:
interface IChildBeater { }
Then have them implement it:
class Child {
public bool IsBeaten { get; private set; }
public void Beat(IChildBeater beater) {
IsBeaten = true;
}
}
class Mother : IChildBeater { ... }
class Father : IChildBeater { ... }
class BullyFromDownTheStreet : IChildBeater { ... }

This is usually achieved by using separate assemblies and the InternalsVisibleToAttribute. When you mark the set with internal classes within the current assembly will have access to it. By using that attribute, you can give specific other assemblies access to it. Remember by using Reflection it will still always be editable.

C# getter and setter shorthand

If my understanding of the internal workings of this line is correct:
public int MyInt { get; set; }
Then it behind the scenes does this:
private int _MyInt { get; set; }
Public int MyInt {
get{return _MyInt;}
set{_MyInt = value;}
}
What I really need is:
private bool IsDirty { get; set; }
private int _MyInt { get; set; }
Public int MyInt {
get{return _MyInt;}
set{_MyInt = value; IsDirty = true;}
}
But I would like to write it something like:
private bool IsDirty { get; set; }
public int MyInt { get; set{this = value; IsDirty = true;} }
Which does not work. The thing is some of the objects I need to do the IsDirty on have dozens of properties and I'm hoping there is a way to use the auto getter/setter but still set IsDirty when the field is modified.
Is this possible or do I just have to resign myself to tripling the amount of code in my classes?

You'll need to handle this yourself:
private bool IsDirty { get; set; }
private int _myInt; // Doesn't need to be a property
Public int MyInt {
get{return _myInt;}
set{_myInt = value; IsDirty = true;}
}
There is no syntax available which adds custom logic to a setter while still using the automatic property mechanism. You'll need to write this with your own backing field.
This is a common issue - for example, when implementing INotifyPropertyChanged.

Create an IsDirty decorator (design pattern) to wrap some your properties requiring the isDirty flag functionality.
public class IsDirtyDecorator<T>
{
public bool IsDirty { get; private set; }
private T _myValue;
public T Value
{
get { return _myValue; }
set { _myValue = value; IsDirty = true; }
}
}
public class MyClass
{
private IsDirtyDecorator<int> MyInt = new IsDirtyDecorator<int>();
private IsDirtyDecorator<string> MyString = new IsDirtyDecorator<string>();
public MyClass()
{
MyInt.Value = 123;
MyString.Value = "Hello";
Console.WriteLine(MyInt.Value);
Console.WriteLine(MyInt.IsDirty);
Console.WriteLine(MyString.Value);
Console.WriteLine(MyString.IsDirty);
}
}

You can make it simple or complex. It depends on how much work you want to invest. You can use aspect oriented programming to add the aspect via an IL weaver into the IL code with e.g. PostSharp.
Or you can create a simple class that does handle the state for your property. It is so simple that the former approach only pays off if you have really many properties to handle this way.
using System;
class Dirty<T>
{
T _Value;
bool _IsDirty;
public T Value
{
get { return _Value; }
set
{
_IsDirty = true;
_Value = value;
}
}
public bool IsDirty
{
get { return _IsDirty; }
}
public Dirty(T initValue)
{
_Value = initValue;
}
}
class Program
{
static Dirty<int> _Integer;
static int Integer
{
get { return _Integer.Value; }
set { _Integer.Value = value; }
}
static void Main(string[] args)
{
_Integer = new Dirty<int>(10);
Console.WriteLine("Dirty: {0}, value: {1}", _Integer.IsDirty, Integer);
Integer = 15;
Console.WriteLine("Dirty: {0}, value: {1}", _Integer.IsDirty, Integer);
}
}
Another possibility is to use a proxy class which is generated at runtime which does add the aspect for you. With .NET 4 there is a class that does handle this aspect already for you. It is called ExpandObject which does notify you via an event when a property changes. The nice things is that ExpandoObject allows you to define at runtime any amount of properties and you get notifications about every change of a property. Databinding with WPF is very easy with this type.
dynamic _DynInteger = new ExpandoObject();
_DynInteger.Integer = 10;
((INotifyPropertyChanged)_DynInteger).PropertyChanged += (o, e) =>
{
Console.WriteLine("Property {0} changed", e.PropertyName);
};
Console.WriteLine("value: {0}", _DynInteger.Integer );
_DynInteger.Integer = 20;
Console.WriteLine("value: {0}", _DynInteger.Integer);
Yours,
Alois Kraus

I'm going to add on to Simon Hughes' answer. I propose the same thing, but add a way to allow the decorator class to update a global IsDirty flag automatically. You may find it to be less complex to do it the old-fashioned way, but it depends on how many properties you're exposing and how many classes will require the same functionality.
public class IsDirtyDecorator<T>
{
private T _myValue;
private Action<bool> _changedAction;
public IsDirtyDecorator<T>(Action<bool> changedAction = null)
{
_changedAction = changedAction;
}
public bool IsDirty { get; private set; }
public T Value
{
get { return _myValue; }
set
{
_myValue = value;
IsDirty = true;
if(_changedAction != null)
_changedAction(IsDirty);
}
}
}
Now you can have your decorator class automatically update some other IsDirty property in another class:
class MyObject
{
private IsDirtyDecorator<int> _myInt = new IsDirtyDecorator<int>(onValueChanged);
private IsDirtyDecorator<int> _myOtherInt = new IsDirtyDecorator<int>(onValueChanged);
public bool IsDirty { get; private set; }
public int MyInt
{
get { return _myInt.Value; }
set { _myInt.Value = value; }
}
public int MyOtherInt
{
get { return _myOtherInt.Value; }
set { _myOtherInt.Value = value; }
}
private void onValueChanged(bool dirty)
{
IsDirty = true;
}
}

I have created a custom Property<T> class to do common operations like that. I haven't used it thoroughly yet though, but it could be used in this scenario.
Code can be found here: http://pastebin.com/RWTWNNCU
You could use it as follows:
readonly Property<int> _myInt = new Property<int>();
public int MyInt
{
get { return _myInt.GetValue(); }
set { _myInt.SetValue( value, SetterCallbackOption.OnNewValue, SetDirty ); }
}
private void SetDirty( int oldValue, int newValue )
{
IsDirty = true;
}
The Property class handles only calling the passed delegate when a new value is passed thanks to the SetterCallbackOption parameter. This is default so it can be dropped.
UPDATE:
This won't work apparently when you need to support multiple types (besides int), because the delegate won't match then. You could ofcourse always adjust the code to suit your needs.

Promote field's IBindingList to class's

I'm creating a table from a dynamically created IBindingList using
class TableBuilder
{
private Type m_TableType;
// ... create and define m_TableType here
public IBindingList CreateTable()
{
return Activator.CreateInstance(m_TableType) as IBindingList;
}
}
class DynamicTable : IBindingList
{
private IBindingList m_theList;
private TableBuilder m_tableBuilder;
public DynamicTable(TableBuilder tableBuilder)
{
m_tableBuilder = tableBuilder;
m_theList = tableBuilder.CreateTable();
}
public void LoadData()
{
// ...
}
}
I would like to promote the IBindingList functionality of m_theList to the level of the class so I can make calls like
var myTable = new DynamicTable(someTableBuilder);
int count = myTable.Count;
myTable.LoadData();
count = myTable.Count;
How can I get all the m_theList public members to be members of DynamicTable. I can not derive DynamicTable from m_TableType since it is only known at run time.
-Max

You will have to do it as old subclassing, implement the interface and in each method call the corresponding method in m_theList:
//methods
public void AddIndex(PropertyDescriptor property)
{
m_theList.AddIndex(property);
}
public object AddNew()
{
return m_theList.AddNew();
}
//properties
public bool AllowEdit
{
get { return m_theList.AllowEdit; }
}
....
//for events you can use add/remove syntax
public event ListChangedEventHandler ListChanged
{
add { m_theList.ListChanged += value; }
remove { m_theList.ListChanged -= value; }
}
....
//indexer...
public object this[int index]
{
get
{
return m_theList[index];
}
set
{
m_theList[index] = value;
}
}