c# - 匿名方法最短语法

Question

关于匿名方法，并给出第一个参数作为 Func 的方法“WriteConditional”，有没有办法甚至消除额外的“() => ”语法？

看起来你应该能够，因为只要没有额外的重载接受字符串，它就明确，对吗？

void Program()
{
  IDictionary<string,string> strings = new Dictionary<string,string>() { {"test","1"},{"test2","2"}};

  //seems like this 'should' work, because WriteConditional has no other overload
  //that could potentially make this ambiguous
  WriteConditional(strings["test"],"<h3>{0}</h3>");

  //since WriteConditional_2 has two overloads, one that has Func<string> and another with string,
  //the call could be ambiguous, so IMO you'd definitely have to "declare anonymous" here:
  WriteConditional_2(()=>strings["test"],"<h3>{0}</h3>");      
}

void WriteConditional(Func<string> retriever, string format)
{
   string value = retriever.Invoke();
   if(string.IsNullOrEmpty(value)==false)
      Console.WriteLine(string.Format(format,value));
}

void WriteConditional_2(Func<string> retriever, string format)
{
   string value = retriever.Invoke();
   if(string.IsNullOrEmpty(value)==false)
      Console.WriteLine(string.Format(format,value));
}

void WriteConditional_2(string value, string format)
{
   if(string.IsNullOrEmpty(value)==false)
      Console.WriteLine(string.Format(format,value));
}

Answer 1

不，没有这样的方法。但是，您可以作弊并提供自己的重载:

void WriteConditional(Func<string> retriever, string format)
{
   var value = retriever();
   if(string.IsNullOrEmpty(value)==false)
      Console.WriteLine(string.Format(format,value));
}

void WriteConditional(string value, string format)
{
   WriteConditional(() => value, format);
}