|= caching thing , C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Microsoft (R) Visual C# Compiler version 2.9.0.63208 (958f2354)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        static bool objectIsDirty;
        
        public static void Main(string[] args)
        {
            objectIsDirty = false;
            bool tmp = InspectObject();
            objectIsDirty |= tmp;
            
            Log("1");
            
            objectIsDirty = false;
            objectIsDirty |= InspectObject();
            
            Log("1");
            
            
            objectIsDirty = false;
            objectIsDirty = objectIsDirty || InspectObject();
            
            Log("1");
            
            
            objectIsDirty = false;
            objectIsDirty = InspectObject() || objectIsDirty;
            
            Log("1");
        }
        
        static bool InspectObject()
        {
            objectIsDirty = true;
            
            return false;
        }
        
        static void Log(string key)
        {
            if (objectIsDirty) 
                Console.WriteLine(key+": True");
            else 
                 Console.WriteLine(key+": False");
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,26 sec, absolute running time: 0,13 sec, cpu time: 0,11 sec, average memory usage: 15 Mb, average nr of threads: 3, absolute service time: 0,42 sec