How can I tell if a streamwriter is closed?

Question

I'm using a streamwriter in combination with a background worker, for logging.

As such, I have

System::Void
MyUI::execBWorker_DoWork(System::Object^  sender, System::ComponentModel::DoWorkEventArgs^  e) {

String^ outputPath = _clr::Settings::ApplicationLogPath("_log.txt", true, false);
logfile_ = gcnew StreamWriter(outputPath,true);

DoStuff();
logfile_->Close();
}

Things in the DoStuff() method raise the Progress event.

System::Void
MyUI::execBWorker_ProgressChanged(System::Object^  sender, System::ComponentModel::ProgressChangedEventArgs^  e) {
logfile_->WriteLine("something");
}

I think this really smells. How can I make it better, or at least how can I check the logfile hasn't been closed? There are a lot of messages, so I'm concerned about opening and closing the logfile continuously.

score 26 · Accepted Answer · answered Jul 04 '12 at 06:55

26

If the StreamWriter is closed, the BaseStream property will return null.

answered Jul 04 '12 at 06:55

leppie

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Cool - answers the technical part. – Melanie Jul 04 '12 at 07:22
@Melanie: `File::AppendText` might be useful in your case. – leppie Jul 04 '12 at 07:24
2

This answer is wrong - for me it did not return null and Resharper is also also warning me that (streamWriter.BaseStream != null) is always true. – Enes Sadık Özbek May 08 '18 at 10:48
@Trojaner On .NET desktop this is the case. Are you using something else? – leppie May 08 '18 at 11:52
@Trojanerand does in .NET Core too https://github.com/dotnet/coreclr/blob/master/src/mscorlib/shared/System/IO/StreamWriter.cs#L215 – leppie May 08 '18 at 11:55
I'm using .NET 3.5 – Enes Sadık Özbek May 08 '18 at 17:06
@leppie Your link is dead, correct permalink: https://github.com/dotnet/coreclr/blob/c8ab9ee7f144dd8b42762a06ffd9d9b40b918490/src/mscorlib/shared/System/IO/StreamWriter.cs#L215 – Tejes May 31 '21 at 10:06
In my case, using .net 6 console, `StreamWriter.BaseStream` will never be null, I use the readonly property `StreamWriter.BaseStream.CanSeek = false` to determine if the stream is closed – MrCalvin Nov 16 '22 at 06:10

How can I tell if a streamwriter is closed?

1 Answers1