c# - 不带日期时间函数(如 ToShortDateString())的 DateTime 等类型的隐式运算符

Question

我想使用带有隐式运算符的泛型类。问题是使用底层函数。我认为最好的描述是我的代码

public class AnnotationField<T>
{
    public T Value { get; set; }
    public bool IsNullValue { get; set; }
    public CompareTypes CompareType { get; set; }

    public static implicit operator T(AnnotationField<T> temp)
    {
        return temp.Value;
    }

    public static implicit operator AnnotationField<T>(T temp)
    {
        Type correctType = Nullable.GetUnderlyingType(typeof(T)) ?? typeof(T);
        AnnotationField<T> annotationField = new AnnotationField<T> {};
        annotationField.Value = (T)Convert.ChangeType(temp, correctType);
        return annotationField;
    }
}

使用:

public AnnotationField<DateTime> Birthday { get; set; }

myObject.Birthday = new DateTime(1986, 7, 2); // <- Works
myObject.Birthday.ToShortDateString();  // <- Compiler-Error !
myObject.Birthday.Value.ToShortDateString();  // <- Works

如果 DateTime 可以为空，我需要另一个方法调用

public AnnotationField<DateTime?> Birthday { get; set; }

myObject.Birthday.Value.Value.ToShortDateString(); // <- Works but is not really usable!

Answer 1

添加 extension method在 AnnotationField<DateTime?>输入:

public static class Extensions 
{
    public static string ToShortDateString(this AnnotationField<DateTime?> item)
    {
        return item.Value.Value.ToShortDateString();
    }
}

这样，您就可以调用:

public AnnotationField<DateTime?> Birthday { get; set; }

myObject.Birthday.ToShortDateString();