Wilfried Mestdagh wrote:
Hello,

I have a compiler warning in following code 'F might not be
initialized', at the M.LoadFromStream(F); line.

M := TMemoryStream.Create;
try
for n := 0 to FFiles.Count - 1 do begin
try
F := TFileStream.Create(FFiles[n], Read or fmShareDenyWrite);
except
TriggerWarning('Could not open ''' + FFiles[n] + '''');
Continue;
end;
M.LoadFromStream(F);
F.Free;

All the above can be replaced with this:

try
M.LoadFromFile(FFiles[n]);
except
on EFileStreamError do begin
TriggerWarning();
continue;
end;
end;

(The exact exception class might not be accurate for all versions of
Delphi. I don't remember EFileStreamError from Delphi 5, but it's in
Delphi 2005.)

if not DeleteFile(FFiles[n]) then
TriggerWarning('Cannot delete file ''' + FFiles[n] + ''', will not transmit it.')
else
// Todo: add to database and transmit it
end;
finally
M.Free;
end;

However unless my brain is damaged due to late hours work, it should
always be initialized because if exception occure I 'continue' the loop.

The compiler sometimes has trouble following execution paths into or out
of "except" blocks for the purpose of detecting usage of variables.

What I'm trying to do is read files generated by another application,
open them, do something with it and delete it. The other application may
not change the file after I open it of course.

You should take a look at the File_Flag_DClose flag, which you
can pass to CreateFile when you open a file. You can keep the file open
as long as you want, and when you close it, the S will delete it for
you. It makes sure no one else opens it without also specifying "delete"
permission. Instead of using a TFileStream or a TMemoryStream, you would
need to call CreateFile directly, and then perhaps use the returned
handle in a THandleStream.

Rustamas Narusevicius wrote:
This warning appears, because F can be equal to nil if TFileStream.Create
raises exception. In this case youll handle exception, but not initialize
your variable F.

If TFileStream.Create raises an exception, then F will remain
uninitialized. However, the "except" clause catches the exception and uses
"Continue" to skip the rest of the body of the loop, so F never gets used,
either. The warning is incorrect.