您可以使用
List<string> sList = new List<string>() { "1","2" };
创建一个新列表并添加2个项目. {“1”,“2”} – 部分仅起作用,因为List< T>实现了Add()方法.
我的问题：{}类似于操作符,可以重载,例如两次添加项目
is {} something like a operator and can it be overloaded e.g. to add
items twice
任何提供Add方法,内置或作为扩展方法(starting from C#-6)的集合类型都可以使用{}语法提供的集合初始值设定项.如果您的Add方法将相同的项目两次添加到该集合,那么它就是这样做的.
如果您希望更改{}的行为,则必须覆盖或重载集合上的Add方法.
一些额外的规格优点(取自this answer)：
C# Language Specification – 7.5.10.3 Collection Initializers
The collection object to which a collection initializer is applied must be of a type that implements System.Collections.IEnumerable or a compile-time error occurs. For each specified element in order,the collection initializer invokes an Add method on the target object with the expression list of the element initializer as argument list,applying normal overload resolution for each invocation. Thus,the collection object must contain an applicable Add method for each element initializer.
