Nullable类型之间的转换

Question

.NET 4.0中是否有转换器支持可空类型之间的转换以缩短指令,例如:

bool? nullableBool = GetSomething();
byte? nbyte = nullableBool.HasValue ? (byte?)Convert.ToByte(nullableBool.Value) : null;

Answer 1

我会写一个扩展方法:

public static class Extensions
{
    public static TDest? ConvertTo<TSource, TDest>(this TSource? source) 
        where TDest: struct 
        where TSource: struct
    {
        if (source == null)
        {
            return null;
        }
        return (TDest)Convert.ChangeType(source.Value, typeof(TDest));
    }
}

然后:

bool? nullableBool = true;
byte? nbyte = nullableBool.ConvertTo<bool, byte>();

Answer 2

据我所知，情况并非如此。
您可以编写一个像这样的辅助方法：

public Nullable<TTarget> NullableConvert<TSource, TTarget>(
          Nullable<TSource> source, Func<TSource, TTarget> converter)
    where TTarget: struct
    where TSource: struct
{
    return source.HasValue ? 
               (Nullable<TTarget>)converter(source.Value) : 
               null;
}

像这样称呼它：

byte? nbyte = NullableConvert(nullableBool, Convert.ToByte);