Use of the Conditional attribute

1. When a method marked as conditional by [Conditional("preprocessing symbol")] is called, the presence or absence of the specified preprocessing symbol determines whether this call is included or omitted. Include the call if the symbol is defined; otherwise omit the call. Using Conditional is an alternative to enclosing #if and #endif inner methods.

#define TRACE_ON //若没有此宏定义预处理，则Trace中的Msg(string msg)方法调用将被忽略
using System;
using System.Diagnostics;

public class Trace
{
    
    
    [Conditional("TRACE_ON")]
    public static void Msg(string msg)
    {
    
    
        Console.WriteLine(msg);
    }
}

public class ProgramClass
{
    
    
    static void Main()
    {
    
    
        Trace.Msg("Now in Main...");
        Console.WriteLine("Done.");
    }
}

If the TRACE_ON identifier is not defined, no trace output will be displayed.

Reference documentation
Conditional (C# Programming Guide)

2. The document says that Conditional can achieve the effect of or, but after trying to achieve the effect of and, it doesn't work:

public class Trace
{
    
    
    [Conditional("TRACE_ON"),Conditional("TRACE_ON_2")] //可以实现或的效果
    public static void Msg(string msg)
    {
    
    
        UnityEngine.Debug.Log("msg:" + msg);
    }

    [Conditional("TRACE_ON")]//可以实现或的效果
    [Conditional("TRACE_ON_2")]
    public static void Msg2(string msg)
    {
    
    
        UnityEngine.Debug.Log("msg:" + msg);
    }
}

The effect of and cannot be achieved in the following way (there is no way to achieve and):

3. It has no effect to test the attribute condition of the class, no matter whether DEBUG is defined or not, it has no effect