c# - 我可以过滤此委托(delegate)以检查是否重复任何名称并删除

Question

所以我有这个代表:

   private static readonly Func<GetAddress, GetNames> ConvertAddress = a => new Address() {
        StreetNumber = a.streetNumber,
        City = a.city,
        State = a.state,
        zip = a.zip,
        firstName = a.firstName,
        LastName = a.lastName 
    };

我这样调用它:

ADRESS = o.Addresses.Select(ConvertAddress).First(), ... 

所以我想对名字和姓氏进行某种筛选。如果它们被使用过一次，我希望下次调用时它们为空。不是 null 的地址，而是名称。

所以如果 john johnson 经历了两次，我希望 john johnson 第二次经历这个时将他的名字分配给“”或 null。

Answer 1

显然，您需要在调用的每个实例之间共享某种状态。最简洁的方法是将其传入，这样您的函数就会变成如下所示:

private static readonly Func<GetAddress, ISet<string>, GetNames> ConvertAddress = a, usedNames => 
{ 
var fullName = string.Format("{0} {1}", a.FirstName, a.LastName);
var fullNameHasBeenUsed = usedNames.Contains(fullName);
usedNames.Add(fullName);
return new Address() {
    StreetNumber = a.streetNumber,
    City = a.city,
    State = a.state,
    zip = a.zip,
    firstName = fullNameHasBeenUsed ? null : a.firstName,
    LastName = fullNameHasBeenUsed ? null : a.lastName 
};}

然后你会这样调用它:

var usedFirstNames = new HashSet<string>();
ADRESS = o.Addresses.Select(a => ConvertAddress(a, usedFirstNames)).First()