使方法泛型

本文关键字：泛型 方法 | 更新日期: 2023-09-27 17:53:22

我有一个从特定对象中提取日期名称的方法，像这样:

private string ExtractWeekDayNames(FiscalReceipt fiscalReceipt)
    {
        string retVal = "";
        Dictionary<string, bool> WeekDays = 
            new Dictionary<string, bool>() {
                                            { "Sun", fiscalReceipt.Sunday },
                                            { "Mon", fiscalReceipt.Monday },
                                            { "Tue", fiscalReceipt.Tuesday },
                                            { "Wed", fiscalReceipt.Wednesday },
                                            { "Thu", fiscalReceipt.Thursday },
                                            { "Fri", fiscalReceipt.Friday },
                                            { "Sat", fiscalReceipt.Saturday }
                                            };

        //Find week days
        foreach (var item in WeekDays)
        {
            if (item.Value == true)
                retVal += item.Key + ",";
        }
        if (!string.IsNullOrEmpty(retVal))
            retVal = retVal.Substring(0, retVal.Length - 1);
        return retVal;
    }

我也有一个类似的方法来执行相同的操作但是有不同类型的参数，比如:

private string ExtractWeekDayNames(NonFiscalReceipt nonFiscalReceipt)
{
    ...
}

NonFiscalReceipt也有Sunday, Monday等属性。

我如何用一个方法代替这两个方法?

使方法泛型

public class FiscalReceipt : Receipt{
FiscalReceipt specific fields
}
public class NonFiscalReceipt : Receipt{
NonFiscalReceipt specific fields..
}
public class Receipt{
fields common to both classes
}
private string ExtractWeekDayNames(Receipt receipt){
}

两种类型的收据都继承自收据，也就是说，你可以传入其中一种，仍然会有所有的字段:)

您需要为您的类创建一个要实现的公共接口，以便该方法可以接受实现该接口的任何内容。

interface IReceipt
{
    bool Sunday {get; }
    bool Monday {get; }
    ...
    bool Saturday {get; }
}

那么你的方法应该是这样的:

private string ExtractWeekDayNames<T>(T receipt) where T : IReceipt
{
    string retVal = "";
    Dictionary<string, bool> WeekDays = 
        new Dictionary<string, bool>() {
                                        { "Sun", receipt.Sunday },
                                        { "Mon", fiscalReceipt.Monday },
                                        { "Tue", receipt.Tuesday },
                                        { "Wed", receipt.Wednesday },
                                        { "Thu", receipt.Thursday },
                                        { "Fri", receipt.Friday },
                                        { "Sat", receipt.Saturday }
                                        };

    //Find week days
    foreach (var item in WeekDays)
    {
        if (item.Value == true)
            retVal += item.Key + ",";
    }
    if (!string.IsNullOrEmpty(retVal))
        retVal = retVal.Substring(0, retVal.Length - 1);
    return retVal;
}

然而，正如juharr和Remy Grandin在注释中正确地写道——在这种情况下不需要泛型——您可以简单地将接口传递给方法:

private string ExtractWeekDayNames(IReceipt receipt) 
{
    string retVal = "";
    Dictionary<string, bool> WeekDays = 
        new Dictionary<string, bool>() {
                                        { "Sun", receipt.Sunday },
                                        { "Mon", receipt.Monday },
                                        { "Tue", receipt.Tuesday },
                                        { "Wed", receipt.Wednesday },
                                        { "Thu", receipt.Thursday },
                                        { "Fri", receipt.Friday },
                                        { "Sat", receipt.Saturday }
                                        };

    //Find week days
    foreach (var item in WeekDays)
    {
        if (item.Value == true)
            retVal += item.Key + ",";
    }
    if (!string.IsNullOrEmpty(retVal))
        retVal = retVal.Substring(0, retVal.Length - 1);
    return retVal;
}

为NonFiscalReceipt和FiscalReceipt创建包含共同属性的基接口:

public interface IReceipt
{
   bool Sunday{get;}
   ......
}

替换方法签名:private string ExtractWeekDayNames(IReceipt fiscalReceipt)

尽量使用DayOfWeek enum。

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