c# - 通过匿名方法分配匿名类型的属性

Question

我是 C# 函数方面的新手，如果这个问题很蹩脚，我很抱歉。

给定以下错误代码:

var jobSummaries = from job in jobs
                   where ...
                   select new 
                   {
                        ID = job.ID,
                        Description = job.Description,
                        FileName = (job) => {
                                  // primitive logic not 
                                  // worth to become a named method
                                  try { return job.Files[0].LocalName); }
                                  catch { return null as string; }
                                 }
                   };

此代码产生以下合理的编译器错误:

cannot assign lambda expression to anonymous type property

上面的代码会将委托(delegate)设置为 FileName 属性。但这不是我的目的。我希望代码像这样工作但不命名方法:

var jobSummaries = from job in jobs
                   where ...
                   select new 
                   {
                        ID = job.ID,
                        Description = job.Description,
                        FileName = this.ExtractFileName(job)
                   };

...
private string ExtractFileName(Job job)
{
     try { return Path.GetFileName(job.Files[0].LocalName); }
     catch { return null as string; }
}

有什么建议吗？

Answer 1

要直接调用匿名函数，这是可行的:

int result = new Func<int, int>( (int i) =>{ return i + 5; } ).Invoke(3);
// result = 8

但我同意，int result = (i => i + 5)(3); 会更酷 =)