Delphi: How to catch TStreamWriter Disk full error? - delphi

Question

I wonder, why this code does not catch a 'Disk Full' error like it should?
This is important because the user may lose their data if they do not notice that the saving failed.
I don't get this...
procedure TForm2.Button1Click(Sender: TObject);
var
Writer: TStreamWriter;
n : integer;
begin
Writer := TStreamWriter.Create('MyUTF8Text.txt', false, TEncoding.UTF8);
Try //Finally
Try //Except
for n := 1 to 1000 do
begin
Writer.WriteLine('Testing text writing to the UTF-8 file.');
end;
Except
on E: Exception do
begin
ShowMessage('Exception Class name: ' + E.ClassName);
ShowMessage('Exception Message: ' + E.Message);
end;
end; // except
Finally
Writer.Free();
End; //finally
end;
"BTW. 'Writer might not be initialized' warning, is it serious really?"
Edit: There was this warning because TStreamWriter.Create was after TRY.
Thanks for your advice I corrected that line of code to the correct location before(!) the TRY.

Answer 1

Try This:
procedure WriteStream;
var
Writer: TStreamWriter;
fs: TFileStream;
s: String;
n, bytesWritten : integer;
begin
bytesWritten := 0;
fs := TFileStream.Create('MyUTF8Text.txt', fmCreate);
try
//avoid warning by initiaizing before try
Writer := TStreamWriter.Create(fs);
try //Finally
try //Except
for n := 1 to 10 do
begin
s := 'Testing text writing to the UTF-8 file.' + '#13#10';
//keep count of bytes written
bytesWritten := bytesWritten + TEncoding.UTF8.GetByteCount(s);
Writer.Write(s);
end;
Writer.Flush;
Writer.Close;
//Check stream size to make sure all bytes written
if bytesWritten <> Writer.BaseStream.Size then
raise Exception.Create(String.Format('Expected %d bytes, wrote %d', [Writer.BaseStream.Size, bytesWritten]));
except
on E: Exception do
begin
Showmessage('Exception Class name: ' + E.ClassName);
Showmessage('Exception Message: ' + E.Message);
end;
end; // except
finally
Writer.Free; // Will only free if it has been constructed
end; //finally
finally
fs.Free;
end;
end;