[fpc-devel]Weird isn't it ?

[Michael.VanCanneyt at Wisa.be]

On Wed, 12 Feb 2003, Maly wrote:

> Hi,
>
> i wrote some unit to handle my own FS :> but that's not
> important. well, i've got a constructor looking like this:
>
> constructor CFile.Create(var AFS:CDataFile;APath:string);
>  var SavedPath : string;
>  begin
>   FFS:=AFS;
>   SavedPath:=AFS.GetCurrentPath;
> //  Writeln(SavedPath);
>   FFileName:=CopyUntilReversed(APath,'/');
>   FFilePath:=APath;
>   AFS.ChDir(FFilePath);
>   FIndex:=AFS.GetFileID(FFileName);
>   if FIndex=0 then
>    raise EDataFileException.Create('file '+APath+'doesn''t exist');
>   if FFS.Header.Files[FIndex].IsCompressed then
>    DataStream:=TDataFileCompressedStream.Create(FFS,FIndex)
>   else
>    DataStream:=TDataFileStream.Create(AFS,FIndex);
>   FFS.ChDir(SavedPath);
>  end;
>
> this code is 100% correct,

It is not. You should AT LEAST put the

   AFS.ChDir(FFilePath);
   FFS.ChDir(SavedPath);

In a try/finally block:

   AFS.ChDir(FFilePath);
   Try
     FIndex:=AFS.GetFileID(FFileName);
     if FIndex=0 then
       raise EDataFileException.Create('file '+APath+'doesn''t exist');
     if FFS.Header.Files[FIndex].IsCompressed then
       DataStream:=TDataFileCompressedStream.Create(FFS,FIndex)
     else
        DataStream:=TDataFileStream.Create(AFS,FIndex);
   Finally
      FFS.ChDir(SavedPath);
   end;

This is one thing. Secondly, it sounds like you have some memory buffer
overrun. Did you try using the -gh option ? the heaptrc unit gives you some
extra possibilities.


> but in some specific circumstances
> it works buggy, the variables(class's fields) have weird
> values(like 0 or ''). when I uncomment the commented line
> the results are ok. so how's that possible a writeln can
> fix the code? it does only print the 'debug-info' :>? it
> shouldn't change anything. the point is i don't need that
> line infact i don't want it at all. :/
> i guess it has something to do with optimiser.

Did you try running the code without optimization ?

Michael.