c# - 包含函数和可选参数的字典

Question

我有一个字典设置如下:

    private Dictionary<string, Promotion> availablePromotions = new Dictionary<string, Promotion>()
    {
        { "BestHorseRacingFreeBetSidebarOffers", Client.GetHorseRacingSignUpOffersSidebarWidget() },
        { "BestHorseRacingBettingSidebarOffers", Client.GetHorseRacingBettingOffersSidebarWidget() },
        { "BestHorseRacingBettingOffers", Client.GetBestHorseRacingBettingOffersWidget() },
        { "BestHorseRacingFreeBetOffers", Client.GetBestHorseRacingSignUpOffersWidget()  },
        { "BestFootballBettingOffers", Client.GetBestFootballBettingOffersWidget() },
        { "TopFootballBettingOffer", Client.GetFootballBettingOfferWidget() },
        { "BestFootballFreeBetOffers", Client.GetBestFootballSignUpOffersWidget() },
        { "TopFootballFreeBetOffer", Client.GetTopFootballSignUpOfferWidget() },
        { "TopHorseRacingFreeBetOffer", Client.GetTopHorseRacingSignUpOfferWidget() },
        { "TopHorseRacingBettingOffer", Client.GetTopHorseRacingBettingOfferWidget() }
    };

我有一个 View 组件调用函数，它根据“promotionType”将“vm”应用于字典中的函数:

  public IViewComponentResult Invoke(string promotionType, CompanyEnum? companyId)
    {
        Promotion vm;

        if(promotionType == "TopFreeBetOffer")
        {
            vm = Client.GetTopBookmakerSpecificSignUpOfferWidget((CompanyEnum)companyId);
        }
        else if (promotionType == "BestFreeBetOffers")
        {
            vm = Client.GetBestBookmakerSpecificSignUpOffersWidget((CompanyEnum)companyId);
        }
        else if (promotionType == "TopBettingOffer")
        {
            vm = Client.GetTopBookmakerSpecificBettingOfferWidget((CompanyEnum)companyId);
        }
        else if (promotionType == "BestBettingOffers")
        {
            vm = Client.GetBestBookmakerSpecificBettingOffersWidget((CompanyEnum)companyId);
        }
        else
        {
            vm = availablePromotions[promotionType];
        }

        return View(vm);
    }

如您所见，我有一些函数采用名为“companyId”的参数。

如何才能将带有参数的函数添加到我的字典中，而不是使用 if 语句？

Answer 1

您可以将委托(delegate)存储在字典中，对于不需要参数的方法，您可以忽略它。通过这种方式，您可以将它们全部存储在其中:

private Dictionary<string, Func<CompanyEnum?, Promotion>> availablePromotions = new Dictionary<string, Func<CompanyEnum?, Promotion>>()
{
    { "BestHorseRacingFreeBetSidebarOffers", companyId => Client.GetHorseRacingSignUpOffersSidebarWidget() },
    { "BestHorseRacingBettingSidebarOffers", companyId => Client.GetHorseRacingBettingOffersSidebarWidget() },
    { "TopFreeBetOffer", companyId => Client.GetTopBookmakerSpecificSignUpOfferWidget(companyId) },
    { "BestFreeBetOffers", companyId => Client.GetBestBookmakerSpecificSignUpOffersWidget(companyId) },
    // ...
};

你的Invoke方法会变得简洁(也许使用TryGetValue):

public IViewComponentResult Invoke(string promotionType, CompanyEnum? companyId)
{
    Promotion vm = availablePromotions[promotionType](companyId);
    return View(vm);
}