struct FileObject
{
    FileObject() : impl(new Impl) {}
    typedef weak_ptr<Impl> Ref;
    
    bool IsOpened() const { return impl->file; }
    void Close() { impl->file.reset(); }
    void Open(const char* fname) { impl->file.reset(new File(fname)); }
    
private:
    struct Impl
    {
        shared_ptr<File> file;
    };
    
    shared_ptr<Impl> impl;
};