Where i need to define INotifyPropertyChanged in case of Base and sub classes

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有刺的猬
有刺的猬 2021-01-25 04:22

i have this Base class:

public abstract class WiresharkFile
{
    protected string _fileName;
    protected int _packets;
    protected int _packets         


        
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  • 2021-01-25 04:54

    Same answer with IIan but for C# 8 and .Net Framework 4.8.

    1. Base Model

    public class ObservableObject : INotifyPropertyChanged
    {
            public event PropertyChangedEventHandler PropertyChanged;
    
            protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
            {
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            }
    
            protected virtual void OnPropertyChanged<T>(Expression<Func<T>> raiser)
            {
                string propName = ((MemberExpression)raiser?.Body).Member.Name;
                OnPropertyChanged(propName);
            }
    
            protected bool Set<T>(ref T field, T value, [CallerMemberName] string name = null)
            {
                if (!EqualityComparer<T>.Default.Equals(field, value))
                {
                    field = value;
                    OnPropertyChanged(name);
                    return true;
                }
                return false;
            }
    }
    

    2. Your Model

    public class Current : ObservableObject
    {
            private string _status;
    
            public Current()
            {
                Status = "Not Connected";
            }
    
            public string Status
            {
                get { return _status; }
                set
                {
                    _status = value;
                    OnPropertyChanged(); // call this to update
                }
            }
    }
    

    3. How to use?

    <Label Content="{Binding Status}"/>
    
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  • 2021-01-25 04:57

    If your xaml is binded to properties of WiresharkFile then a WiresharkFile have to implement the INotifyPropertyChanged, if not it will lead to the memory leaks (Top 3 Memory Leak Inducing Pitfalls of WPF Programming). If your binding is defined only on a Libpcap class then the Libpcap have to implement the INotifyPropertyChanged interface. In my projects I create a base implementation of the INotifyPropertyChanged interface ,and then each base models and base view models just inherits from that implementation. Here some base code: 1. Base implementation:

    public class BaseObservableObject : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
    
        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            var handler = PropertyChanged;
            if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
        }
    
        protected virtual void OnPropertyChanged<T>(Expression<Func<T>> raiser)
        {
            var propName = ((MemberExpression)raiser.Body).Member.Name;
            OnPropertyChanged(propName);
        }
    
        protected bool Set<T>(ref T field, T value, [CallerMemberName] string name = null)
        {
            if (!EqualityComparer<T>.Default.Equals(field, value))
            {
                field = value;
                OnPropertyChanged(name);
                return true;
            }
            return false;
        }
    }
    

    2. Your model (in my opinion):

    public abstract class WiresharkFile:BaseObservableObject
    {
        private string _fileName;
        private int _packets;
        private int _packetsSent;
        private string _duration;
    
        public int Packets
        {
            get { return _packets; }
            set
            {
                _packets = value;
                OnPropertyChanged();
            }
        }
    
        public int PacketsSent
        {
            get { return _packetsSent; }
            set
            {
                _packetsSent = value;
                OnPropertyChanged();
            }
        }
    }
    

    regards,

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