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docs/fundamentals/runtime-libraries/snippets/System/NotSupportedException/Overview/fsharp/BadState1.fs
34 строки
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Genevieve Warren
Remarks for exception types and Registry class (#38930)
03 янв 2024, 22:30
Не верифицирован
03 янв 2024, 22:30
932bcca
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module BadState // <Snippet1> open System.IO open System.Text let main = task { let enc = Encoding.Unicode let value = "This is a string to persist." let bytes = enc.GetBytes value let fs = new FileStream(@".\TestFile.dat", FileMode.Open, FileAccess.Read) let t = fs.WriteAsync(enc.GetPreamble(), 0, enc.GetPreamble().Length) let t2 = t.ContinueWith(fun a -> fs.WriteAsync(bytes, 0, bytes.Length)) let! _ = t2 fs.Close() } main.Wait() // The example displays the following output: // Unhandled Exception: System.NotSupportedException: Stream does not support writing. // at System.IO.Stream.BeginWriteInternal(Byte[] buffer, Int32 offset, Int32 count, AsyncCallback callback, Object state // , Boolean serializeAsynchronously) // at System.IO.FileStream.BeginWrite(Byte[] array, Int32 offset, Int32 numBytes, AsyncCallback userCallback, Object sta // teObject) // at System.IO.Stream.<>c.<BeginEndWriteAsync>b__53_0(Stream stream, ReadWriteParameters args, AsyncCallback callback, // Object state) // at System.Threading.Tasks.TaskFactory`1.FromAsyncTrim[TInstance,TArgs](TInstance thisRef, TArgs args, Func`5 beginMet // hod, Func`3 endMethod) // at System.IO.Stream.BeginEndWriteAsync(Byte[] buffer, Int32 offset, Int32 count) // at System.IO.FileStream.WriteAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken) // at System.IO.Stream.WriteAsync(Byte[] buffer, Int32 offset, Int32 count) // at <StartupCode:fs>.main() // </Snippet1>