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Ingo Klöcker kloecker at
Tue Aug 19 21:41:18 BST 2008

On Tuesday 19 August 2008, Thiago Macieira wrote:
> Ingo Klöcker wrote:
> >The point of using QFile is that you do not have to take care of the
> >file resource yourself. QFile will take care of closing the file.
> > Using a class for handling a resource (e.g. QFile for a file, smart
> > pointers for objects allocated on the heap, etc.) is always
> > preferable to dealing with the resource yourself, because it's so
> > darn easy to leak a resource if you do it yourself.
> That means you shouldn't use fdopen on the handle returned by QFile.
> The handle that QFile returns is closed correctly by QFIle, but if
> you do an fdopen, then you have to remember to fclose.
> So, if you need the FILE* anyways, avoid the complexity and open it
> directly.

I know you will kill me for making the following suggestion. :-)

If QFile is too much overhead then I'd use a boost::shared_ptr with 
custom deleter [1], i.e.

    boost::shared_ptr<FILE> fd_in( fopen(path.toLatin1().data(), "rb"), fclose );
    if ( fd_in.get() == NULL )
       return false;

If you want to close the file explicitly then you call fd_in.reset(). 
Otherwise you don't have to do anything.

Reasons for doing the above:
a) We are coding in C++, right? So let's use the power C++ provides. It 
makes no sense to write error prone code, if there's a way to avoid it.
b) Using boost::shared_ptr is just a compile time dependency.
c) Several KDE packages (kdepimlibs, kdepim) do already have a 
dependency on boost.



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