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Conditional Attribute In C#

In this article, we will discuss conditional attribute in C#.

What Is Conditional Attribute?

Conditional attribute allows you to create conditional methods. In other words, conditional methods are always decorated with conditional attribute.

Syntax

[Conditional("symbol_name")]

If the above syntax, if symbol is defined then conditional method will be invoked else bypassed.

Example

Consider a scenario, where you as a developer wants to write log file for debugging purpose but want to disable logging when system is deployed on production.

So, the code at development time the code would be

//  During development time
#define debug
using System;
using System.Diagnostics;

namespace Test {
  class Program {
    static void Main(string[] args) {
      Program p = new Program();
      p.ExecuteLogic1();
      p.LogMessage("Test Message");
      p.ExecuteLogic2();
      Console.ReadLine();
    } 
    [Conditional("debug")]
    public void LogMessage(string message) {
      Console.WriteLine(message);
    }

    public void ExecuteLogic1() {
      Console.WriteLine("Logic 1");
    }
    public void ExecuteLogic2() {
      Console.WriteLine("Logic 2");
    }
  }
}

Now if you run the above code, you get following output

Picture showing the code with the conditional attribute while running in development mode

Click to Enlarge

The method LogMessage is decorated with conditional attribute. The symbol ‘debug’ is defined using #define and because of the reason LogMessage method is invoked.

Now before system is deployed, you as a developer need to comment #define statement so that LogMessage will be bypassed. So, the previous code would be

//  During production deployment time
//#define debug
using System;
using System.Diagnostics;

namespace Test {
  class Program {
    static void Main(string[] args) {
      Program p = new Program();
      p.ExecuteLogic1();
      p.LogMessage("Test Message");
      p.ExecuteLogic2();
      Console.ReadLine();
    } 
    [Conditional("debug")]
    public void LogMessage(string message) {
      Console.WriteLine(message);
    }

    public void ExecuteLogic1() {
      Console.WriteLine("Logic 1");
    }
    public void ExecuteLogic2() {
      Console.WriteLine("Logic 2");
    }
  }
}

Once you run the above code, you will get following output

Click to Enlarge

Posted By -	Karan Gupta

Posted On -	Saturday, May 27, 2017

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