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The official document: Application. Restart Method (System. Windows. Forms) | Microsoft Docs

directory

 Restart

explore

conclusion

revelation

 Restart

When we use it in the.net Framework, there is nothing special about it and it works, but when we use it in.net core3.0, we throw an InvalidOperation exception.

Application.Restart();
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Why is there such a difference in the same method?

explore

Let’s first look at the exception information:

Process was not started by this object, so requested information cannot be determined.

This object did not start the process, so the requested information cannot be determined.

From this we can infer that this exception is related to process start. The code for the Restart method consists of two parts:

if (string.Equals(str + "\ieexec.exe", currentProcess.MainModule.FileName, StringComparison.OrdinalIgnoreCase))
                {
                    flag = true;
                    ExitInternal();
                    string text = AppDomain.CurrentDomain.GetData("APP_LAUNCH_URL") as string;
                    if (text != null)
                    {
                        Process.Start(currentProcess.MainModule.FileName, text);
                    }
                }
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ProcessStartInfo startInfo = Process.GetCurrentProcess().StartInfo;
            startInfo.FileName = ExecutablePath;
            if (stringBuilder.Length > 0)
            {
                startInfo.Arguments = stringBuilder.ToString();
            }

            ExitInternal();
            Process.Start(startInfo);
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The first piece of code is mainly for executing IEExec.exe, so we won’t focus on it.

The ieexec.exe application is. NET Framework with a program that exists in multiple system whitelists. The IEexec.exe application can be used as a host to run other managed applications started with a URL.

Let’s look at the second part of the code about processes:

ProcessStartInfo startInfo = Process.GetCurrentProcess().StartInfo;
Process.Start(startInfo);
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When I perform, indeed as expected in Process. The GetCurrentProcess () StartInfo InvalidOperation abnormalities, abnormal at this point we will narrow the StartInfo properties.

The.net core version 3.0

public static Process GetCurrentProcess()
        {
            throw null;
        }
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public ProcessStartInfo StartInfo
        {
            get
            {
                throw null;
            }
            set
            {
            }
        }
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The.net Framework version

public static Process GetCurrentProcess()
        {
            return new Process(".", isRemoteMachine: false, Microsoft.Win32.NativeMethods.GetCurrentProcessId(), null);
        }
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public ProcessStartInfo StartInfo { get { if (startInfo == null) { startInfo = new ProcessStartInfo(this); } return startInfo; } set { if (value == null) { throw new ArgumentNullException("value"); } startInfo = value; }}Copy the code

conclusion

At this point we conclude that in.net core3.0, a subsequent call to the StartInfo property will throw an exception anyway because GetCurrentProcess() returns null and the StartInfo get is not instantiated.

revelation

.NET Core 3.0 is the first major release of the.NET Core framework to support desktop applications, and some problems are normal. But as a programmer, you should focus on stability, not just the thrill of new technology. Finally, HERE’s a quote from Lao Tzu for you as you read:

I have three treasures, which I hold and keep. One day kindness, two days thrift, three days do not dare to be the first. Ci Gueng yong; Frugality and energy fixation; Don’t dare to be the first.