PHP語言中，有樣東西叫
Magic Constants，即大家常見的"
__LINE__"，"
__FILE__"等等。
這亦是我渴望在C#出現的東西，因為這對Debug或者是Logging都很有用。
C# 5.0就剛巧新增這個功能，叫做
Caller Information，介紹一下。
取錄自
MSDN，Caller Information有三個主要Attribute，分別為 :
- CallerFilePathAttribute
- Full path of the source file
- CallerLineNumberAttribute
- Line number in the source file at which the method is called.
- CallerMemberNameAttribute
使用方法很簡單，只需把Attribute放置在Optional Parameters前端，就如一般的Class Attribute一樣。
以下面程式碼為例:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Runtime.CompilerServices;
namespace WhoCallMyFunction
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
//Comment lines will not affect the LineNumber.
MyFunction(" I Know That Feel Bro.");
}
private void MyFunction( string WhyCallMe,
[CallerMemberName] string MemberName = "",
[CallerFilePath] string FilePath = "",
[CallerLineNumber] int LineNumber = 0
)
{
Console.WriteLine("\r\n WhyCallMe : {0} \r\n " +
"Time : {1} \r\n " +
"Member name : {2} \r\n "+
"FilePath : {3} \r\n "+
"LineNumber : {4} ",
WhyCallMe, DateTime.Now.ToString(), MemberName, FilePath, LineNumber.ToString());
}
}
}
最後便會輸出
WhyCallMe : I Know That Feel Bro.
Time : 8/11/2012 15:21:32
Member name : Form1_Load
FilePath : c:\Users\Ming\Documents\Visual Studio 2012\Projects\WhoCallMyFunction\WhoCallMyFunction\Form1.cs
LineNumber : 20
雖然這是C# 5.0的新功能，但原來有方法可以令舊版本都支援。
詳細請見:
Using C# 5 caller info attributes when targeting earlier versions of the .NET framework
Calling C# 4/3/2.... Using the new C# 5 Caller Information with C# 2,3,4...
