4
我不明白爲什麼當列表被傳遞到ToString<M>(List<M> list)
方法方法Value(string s)
絕不會爲元素的List<string>
。以下是我從LinqPad中提取的測試代碼。與字符串參數重載方法不會被調用,與對象參數調用該方法,而不是
我在調用正確Value()
方法的同時重複遍歷ToString<M>(List<M> list)
方法的列表時沒有問題。
謝謝!
void Main()
{
var list1 = new List<string>{"one","two","three"};
var list2 = new List<object>{1,2,3};
var list3 = new List<long>{1,2,3};
"Strings".Dump();
ToString<string>(list1);
//list1.ForEach(i=> Value(i)); // proper overload of Value() is called
"Objects".Dump();
ToString<object>(list2);
//list2.ForEach(i=> Value(i));
"Longs".Dump();
ToString<long>(list3);
//list3.ForEach(i=> Value(i));
}
public static string ToString<M>(List<M> list)
{
var sb = new StringBuilder();
foreach(M i in list)
{
sb.AppendFormat("{0},", Value(i));
}
var str = sb.ToString();
str.Dump();
return str;
}
public static string Value(string s)
{
"String".Dump();
return "'" + s + "'";
}
// Define other methods and classes here
public static string Value(object o)
{
"Object".Dump();
return o.ToString();
}
這裏是輸出。這表明價值(String s)將永遠不會被調用
Strings
Object
Object
Object
one,two,three,
Objects
Object
Object
Object
1,2,3,
Longs
Object
Object
Object
1,2,3,