How do I write an exit handler for an F# application?

Question

Subject says it all.

I want some code to run if my application is terminated by, say, ^C.

Just a thought--although you're asking about F# you could probably google for ".Net Application Termination Event" and find more information on the general question of how to handle this sort of issue properly. — Onorio Catenacci, Jul 30 '10 at 12:46

score 5 · Accepted Answer · edited Jan 28 '21 at 18:38

5

Use AppDomain.ProcessExit (http://msdn.microsoft.com/en-us/library/system.appdomain.processexit.aspx):

System.AppDomain.CurrentDomain.ProcessExit.Add(fun _ -> ...)

edited Jan 28 '21 at 18:38

Thomas

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answered Jul 30 '10 at 06:53

Dmitry Lomov

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Maybe ProcessExit (http://msdn.microsoft.com/en-us/library/system.appdomain.processexit.aspx) will be more suitable for case of normal process termination. In simple console example System.AppDomain.CurrentDomain.ProcessExit.Add(fun _ -> printfn "ProcessExit") System.AppDomain.CurrentDomain.DomainUnload.Add(fun _ -> printfn "DomainUnload") it outputs "ProcessExit" after exit. – desco Jul 30 '10 at 08:44
Absolutely! How could I miss it? – Dmitry Lomov Jul 30 '10 at 20:49

score 1 · Answer 2 · answered Jul 30 '10 at 05:22

1

See code below. To handle Ctrl-C in a console app, use the Console.CancelKeyPress event.

// does not work - no exception on Ctrl-C
//System.AppDomain.CurrentDomain.UnhandledException.Add(
//    fun _ -> printfn "app is about to die")

System.Console.CancelKeyPress.Add(
    fun _ -> printfn "app is about to die")
printfn "starting..."
System.Threading.Thread.Sleep(5000)  // press Ctrl-C
printfn "ended"

answered Jul 30 '10 at 05:22

Brian

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Note that this only handles ^C termination, not arbitrary process exit. – Dmitry Lomov Jul 30 '10 at 06:48

How do I write an exit handler for an F# application?

2 Answers2

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