我正在编写一个类,它将创建另一个类的不可变副本,我这样做的方式要求副本接受构造函数中原始类的日期和实例。我知道您不能创建指定参数的构造函数约束,但是是否有一种方法可以使用代码契约来解决它?
public class Copier<o, c>
where o : class, INotifyPropertyChanged
where c : class, c // ideally new(datetime, o)
{
private Dictionary<DateTime, c> copies;
public Copier(o original)
{
this.copies = new Dictionary<DateTime, c>();
original.PropertyChanged +=
this.propertyChangedHandler(object sender, PropertyChangedEventArgs args);
}
private void propertyChangedHandler(object sender, PropertyChangedEventArgs args)
{
var original = sender as o;
var now = DateTime.Now;
this.copies.Add(now, new c(now, original)); // error here
}
}
复制类是由我创建的,从原始类继承,覆盖所有属性为只读,并在构造函数中复制原始类的值。
注意:有一个要求(我强加的)原始对象不能被修改
按照建议,传递一个创建委托:
public class Copier<o, c>
where o : class, INotifyPropertyChanged
where c : class, c // ideally new(datetime, o)
{
private Dictionary<DateTime, c> copies;
private Func<o, DateTime, c> copyFunc;
public Copier(o original, Func<o, DateTime, c> copyFunc)
{
this.copyFunc = copyFunc;
this.copies = new Dictionary<DateTime, c>();
original.PropertyChanged +=
this.propertyChangedHandler(object sender, PropertyChangedEventArgs args);
}
private void propertyChangedHandler(object sender, PropertyChangedEventArgs args)
{
var original = sender as o;
var now = DateTime.Now;
this.copies.Add(copyFunc(now, original));
}
}