我不想再传递 nameof 了
有的时候抛出一个异常，我们需要知道是哪个方法抛出的异常。那么，我们可以通过传递 nameof 来获取调用者的方法名。但是，感觉很烦，每次都要传递 nameof。那么，有没有更好的方法呢？
## CallerLineNumberAttribute
获取调用者的行号。
```csharp
using System;
using System.Runtime.CompilerServices;
public static class Program
{
public static void Main()
{
TraceMessage("Something happened.");
}
public static void TraceMessage(string message,
[CallerLineNumber] int sourceLineNumber = 0)
{
Console.WriteLine("Line: {0} - {1}", sourceLineNumber, message);
}
}
// The example displays the following output:
// Line: 10 - Something happened.
```
## CallerFilePathAttribute
获取调用者的文件路径。
```csharp
using System;
using System.IO;
using System.Runtime.CompilerServices;
public static class Program
{
public static void Main()
{
TraceMessage("Something happened.");
}
public static void TraceMessage(string message,
[CallerFilePath] string sourceFilePath = "")
{
Console.WriteLine("File: {0} - {1}", Path.GetFileName(sourceFilePath), message);
}
}
// The example displays the following output:
// File: Program.cs - Something happened.
```
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## CallerMemberNameAttribute
获取调用者的方法名。
```csharp
using System;
using System.Runtime.CompilerServices;
public static class Program
{
public static void Main()
{
DoProcessing();
}
public static void DoProcessing()
{
TraceMessage("Something happened.");
}
public static void TraceMessage(string message,
[CallerMemberName] string memberName = "")
{
Console.WriteLine("Member: {0} - {1}", memberName, message);
}
}
// The example displays the following output:
// Member: DoProcessing - Something happened.
```
## CallerArgumentExpressionAttribute
获取调用者的参数表达式。C# 10.0 新增。
这个其实很好用，以后再也不用担心 ArgumentException 还需要写一个 nameof 了。
```csharp
using System;
using System.Runtime.CompilerServices;
public static class Program
{
public static void Main()
{
int x = 10;
int y = 20;
Assert(x > y, "x > y");
}
public static void Assert(bool condition, [CallerArgumentExpression("condition")] string message = null)
{
Console.WriteLine("Condition: {0} - {1}", condition, message);
}
}
// The example displays the following output:
// Condition: False - x > y
```
## 总结
通过上面的几个例子，我们可以看到，借助在编译时获取调用者的行号、文件路劲和调用者方法名的特性，我们可以在开发中更加方便的进行日志记录。
## 参考
- [CallerLineNumberAttribute Class](https://learn.microsoft.com/dotnet/api/system.runtime.compilerservices.callerlinenumberattribute?view=net-7.0&WT.mc_id=DX-MVP-5003606)[^1]
- [CallerFilePathAttribute Class](https://learn.microsoft.com/dotnet/api/system.runtime.compilerservices.callerfilepathattribute?view=net-7.0&WT.mc_id=DX-MVP-5003606)[^2]
- [CallerMemberNameAttribute Class](https://learn.microsoft.com/dotnet/api/system.runtime.compilerservices.callermembernameattribute?view=net-7.0&WT.mc_id=DX-MVP-5003606)[^3]
- [CallerArgumentExpressionAttribute Class](https://learn.microsoft.com/dotnet/api/system.runtime.compilerservices.callerargumentexpressionattribute?view=net-7.0&WT.mc_id=DX-MVP-5003606)[^4]
[^1]: https://learn.microsoft.com/dotnet/api/system.runtime.compilerservices.callerlinenumberattribute?view=net-7.0&WT.mc_id=DX-MVP-5003606
[^2]: https://learn.microsoft.com/dotnet/api/system.runtime.compilerservices.callerfilepathattribute?view=net-7.0&WT.mc_id=DX-MVP-5003606
[^3]: https://learn.microsoft.com/dotnet/api/system.runtime.compilerservices.callermembernameattribute?view=net-7.0&WT.mc_id=DX-MVP-5003606
[^4]: https://learn.microsoft.com/dotnet/api/system.runtime.compilerservices.callerargumentexpressionattribute?view=net-7.0&WT.mc_id=DX-MVP-5003606
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