c# - 避免 if/else 的最佳实现

Question

我正在做一个在公司休假的程序，以及在特定假期允许的时间。

我使用了一个带有抽象方法的抽象类:

public abstract class Abstract : TimeLength
{
    public AbstractTest(string employeeCode, string employee, string typeOfHoliday, DateTime startDate, DateTime endDate) : base(startDate, endDate, "")
    {
        TypeOfHoliday = typeOfHoliday;
        Employee = employee;
        EmployeeCode = employeeCode;
    }
    public string EmployeeCode { get; set; }
    public string Employee { get; set; }
    public string TypeOfHoliday { get; set; }

    public abstract bool HolidayValidation(string typeOfHoliday);
}

我使用了这个抽象类固有的多个类，如下所示:

class MarriageVacation : Abstract
{
    public MarriageVacation(string employeeCode, string employee, string typeOfHoliday, DateTime startDate, DateTime endDate) : base(employeeCode, employee, typeOfHoliday, startDate, endDate)
    {
    }

    public override bool HolidayValidation(string typeOfHoliday)
    {
        if (Days() > (int)Holiday.MarriageVacation)
        {
            MessageBox.Show("Marriage Vacation Can only be 5 Days");
            return false;
        }
        else
            return true;
    }
}


class Bereavement : Abstract
{
    public Bereavement(string employeeCode, string employee, string typeOfHoliday, DateTime startDate, DateTime endDate) : base(employeeCode, employee, typeOfHoliday, startDate, endDate)
    {
    }

    public override bool HolidayValidation(string typeOfHoliday)
    {
        if (Days() > (int)Holiday.Bereavement)
        {
            MessageBox.Show("Bereavement Can only be 5 Days");
            return false;
        }
        else
            return true;
    }
}

我在假期使用 Enum在 main 中，我想根据用户的选择注册它:

List<Abstract> holiday = new List<Abstract>();
if(CmbTypeHolidays.Text == Holiday.Bereavement.ToString())
        {
            var holid = new Bereavement(CmbEmpHolidays.Text.Split('-')[0], CmbEmpHolidays.Text.Split('-')[1], CmbTypeHolidays.Text, Convert.ToDateTime(StartDateHolidays.Value), Convert.ToDateTime(EndDateHolidays.Value));

            if (holid.HolidayValidation(CmbTypeHolidays.Text))
            {
                holiday.Add(holid);
                var bindingList = new BindingList<Abstract>(holiday);
                dataGridHolidays.DataSource = bindingList;
                controlPanelHolidays.Visible = false;
            }
        }
        else if (CmbTypeHolidays.Text == Holiday.MarriageVacation.ToString())
        {
            var holid = new MarriageVacation(CmbEmpHolidays.Text.Split('-')[0], CmbEmpHolidays.Text.Split('-')[1], CmbTypeHolidays.Text, Convert.ToDateTime(StartDateHolidays.Value), Convert.ToDateTime(EndDateHolidays.Value));

            if (holid.HolidayValidation(CmbTypeHolidays.Text))
            {
                holiday.Add(holid);
                var bindingList = new BindingList<Abstract>(holiday);
                dataGridHolidays.DataSource = bindingList;
                controlPanelHolidays.Visible = false;
            }
        }

我想知道一个更好的方法来实现这个解决方案或者只是更改将数据插入抽象列表的代码

Answer 1

您需要设置一个工厂，将假日类型名称映射到实现它的类:

private class HolidayConstructorArgs {
    public string EmployeeCode {get;set;}
    public string Employee {get;set;}
    public string TypeOfHoliday {get;set;}
    public DateTime From {get;set;}
    public DateTime To {get;set;}
}

private static readonly IDictionary<string,Func<HolidayConstructorArgs,AbstractHoliday>> HolidayByTypeCode =
    new Dictionary<string,Func<HolidayConstructorArgs,AbstractHoliday>> {
        [$"{Holiday.Bereavement}"] = a => new Bereavement(a.EmployeeCode, a.Employee, a.TypeOfHoliday, a.From, a.To)
    ,   [$"{Holiday.MarriageVacation}"] = a => new MarriageVacation(a.EmployeeCode, a.Employee, a.TypeOfHoliday, a.From, a.To)
    };

现在您可以从字典中获取工厂，并使用它来实例化对象:

if (HolidayByTypeCode.TryGetValue(CmbTypeHolidays.Text, out var factory)) {
    // This is where the "magic" happens:
    // Func<> will invoke the appropriate constructor without a conditional
    var holid = factory(
        new HolidayConstructorArgs {
            EmployeeCode = CmbEmpHolidays.Text.Split('-')[0]
        ,   Employee = CmbEmpHolidays.Text.Split('-')[1]
        ,   TypeOfHoliday = CmbTypeHolidays.Text
        ,   From = Convert.ToDateTime(StartDateHolidays.Value)
        ,   To = Convert.ToDateTime(EndDateHolidays.Value)
        }
    );
    // ... The rest of your code remains the same
}