我们有一个遵循 MVVM 模式的 WPF 项目。
在视图模型中有很多代码,如下所示:
private string m_Fieldname;
public string Fieldname
{
get { return m_Fieldname; }
set
{
m_Fieldname = value;
OnPropertyChanged("Fieldname");
}
}
有没有一种方法可以做到这一点并且需要更少的代码?
像这样的事情会很好:
[NotifyWhenChanged]
public string Fieldname { get; set ; }
你可以看看后锐利 http://www.sharpcrafters.com/。他们甚至有一个样品数据绑定 http://www.sharpcrafters.com/solutions/notifypropertychanged。从那里获取的代码:
/// <summary>
/// Aspect that, when apply on a class, fully implements the interface
/// <see cref="INotifyPropertyChanged"/> into that class, and overrides all properties to
/// that they raise the event <see cref="INotifyPropertyChanged.PropertyChanged"/>.
/// </summary>
[Serializable]
[IntroduceInterface( typeof(INotifyPropertyChanged),
OverrideAction = InterfaceOverrideAction.Ignore )]
[MulticastAttributeUsage( MulticastTargets.Class,
Inheritance = MulticastInheritance.Strict )]
public sealed class NotifyPropertyChangedAttribute : InstanceLevelAspect,
INotifyPropertyChanged
{
/// <summary>
/// Field bound at runtime to a delegate of the method <c>OnPropertyChanged</c>.
/// </summary>
[ImportMember( "OnPropertyChanged", IsRequired = false)]
public Action<string> OnPropertyChangedMethod;
/// <summary>
/// Method introduced in the target type (unless it is already present);
/// raises the <see cref="PropertyChanged"/> event.
/// </summary>
/// <param name="propertyName">Name of the property.</param>
[IntroduceMember( Visibility = Visibility.Family, IsVirtual = true,
OverrideAction = MemberOverrideAction.Ignore )]
public void OnPropertyChanged( string propertyName )
{
if ( this.PropertyChanged != null )
{
this.PropertyChanged( this.Instance,
new PropertyChangedEventArgs( propertyName ) );
}
}
/// <summary>
/// Event introduced in the target type (unless it is already present);
/// raised whenever a property has changed.
/// </summary>
[IntroduceMember( OverrideAction = MemberOverrideAction.Ignore )]
public event PropertyChangedEventHandler PropertyChanged;
/// <summary>
/// Method intercepting any call to a property setter.
/// </summary>
/// <param name="args">Aspect arguments.</param>
[OnLocationSetValueAdvice,
MulticastPointcut( Targets = MulticastTargets.Property,
Attributes = MulticastAttributes.Instance)]
public void OnPropertySet( LocationInterceptionArgs args )
{
// Don't go further if the new value is equal to the old one.
// (Possibly use object.Equals here).
if ( args.Value == args.GetCurrentValue() ) return;
// Actually sets the value.
args.ProceedSetValue();
// Invoke method OnPropertyChanged (our, the base one, or the overridden one).
this.OnPropertyChangedMethod.Invoke( args.Location.Name );
}
}
用法就这么简单:
[NotifyPropertyChanged]
public class Shape
{
public double X { get; set; }
public double Y { get; set; }
}
示例取自 PostSharp 网站并插入以完成答案
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