如何在C#中返回命名元组？

Question

我有一个属性,返回两个类型的项目DateTime.返回这些值时,我必须将它们作为Item1和引用Item2.如何使用自定义名称返回,例如

filter?.DateRanges.From
filter?.DateRanges.To

 

public Tuple<DateTime, DateTime> DateRanges
{
    get
    {
        From = DateTime.Now.AddDays(-1).Date.AddMonths(-1);
        To = DateTime.Now.AddDays(-1).Date;

        if (Preset != 0)
        {
            if (Preset == DatePreset.SpecificRange)
            {
                From = From.Date;
                To = To.Date;
            }
            else
            {
                var dateRange = DateTime.Today.AddDays(-1).GetDateRangeByPreset(Preset);
                From = dateRange.From;
                To = dateRange.To;
            }
        }

        return new Tuple<DateTime, DateTime>(From, To);
    }

用法:

var from = filter?.DateRanges.Item1;
var to = filter?.DateRanges.Item2;

Answer 1

像这样:

public (DateTime Start, DateTime End) DateRanges
{
    get
    {
        return (DateTime.MinValue, DateTime.MaxValue);
    }
}

注意:这需要最新版本的C#和.Net.

顺便提一下,请注意这种使用模式:

var from = filter?.DateRanges.Start;
var to = filter?.DateRanges.End;

这是低效的,因为它会导致创建两个相同的元组.

这个更好:

var range = filter?.DateRanges;

if (range.HasValue)
{
    var from  = range.Value.Start;
    var to    = range.Value.End;
}

但请注意,元组不能为空(它们是值类型),因此您可以像这样编写它:

if (filter != null)
{
    var range = filter.DateRanges;
    var from  = range.Start;
    var to    = range.End;
    ...
}