c#通用转换器

Question

我有一个转换器,允许我在SelectedItems和Generic之间进行转换 List<MyType>

public class SelectedTiposDocsToList : BaseConverter, IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var Selecteditems = value as IList;
        List<MyType> MyTypeList = Selecteditems.Cast<MyType>().ToList();
        return MyTypeList;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
} 

现在这对我来说是一个常见的任务,并希望扩展这个类以允许泛型类型,这可能是这样的吗？

public class SelectedTiposDocsToList : BaseConverter, IValueConverter
{
    public object Convert<T>(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var Selecteditems = value as IList;
        List<T> MyTypeList = Selecteditems.Cast<T>().ToList();
        return MyTypeList;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
} 

这可能吗 ？如果是..如何在XAML上使用这种类型的转换器？

Answer 1

这可以通过一些反射来完成：Type.MakeGenericType获取类型，Activator.CreateInstance调用正确的构造函数，并将MethodInfo.MakeGenericMethod参数提供给Cast。

public Type ConvertType { get; set; }
public object Convert(object value, Type targetType, object parameter,
                      System.Globalization.CultureInfo culture)
{
    var type = typeof(List<>).MakeGenericType(ConvertType);
    var methodInfo = typeof(Enumerable).GetMethod("Cast");
    var genericMethod = methodInfo.MakeGenericMethod(ConvertType);
    var convertTypeList = Activator.CreateInstance(type,
                    genericMethod.Invoke(null, new[] { value }));
    return convertTypeList;
}

您可以使用x:Type 在 XAML 中指定类型。

<myns:SelectedTiposDocsToList x:Key="Conv" ConvertType="{x:Type myns:MyType}" />