Re: Single instance issue

From:

Abhishek Padmanabh <abhishek.padmanabh@gmail.com>

Newsgroups:

microsoft.public.vc.language

Date:

Fri, 21 Dec 2007 05:13:51 -0800 (PST)

Message-ID:

<f72b2d23-9745-48ad-860b-1260d1fbb51d@e23g2000prf.googlegroups.com>

On Dec 21, 5:25 pm, Sarath <CSar...@gmail.com> wrote:

On Dec 21, 5:25 pm, "Alex Blekhman" <tkfx.REM...@yahoo.com> wrote:

"Sarath" wrote:

I've to write a single instance class. there are different
methods to
control the single instance of a program

class CSingleton
{
public:
   CSingleton& GetInstance(){ static CSingleton s; return
s; }

private:
   CSingleton(){}
   ~CSingleton(){}
}

The above code failed to compile in Visual C++ 6.0 but
compiled in
Visual C++ 7.1 and Visual C++ Express 2008. CRT calling
the destructor
of the class. So that Visual C++ 6.0 compilation error is
correct
according to the concept.

I also tried in Dev C++. It was successful but didn't call
the dtor of
the class. Which implementation is correct according to
the standard.

What is the compilation error that VC++ 6.0 gives? The
common approach is to make `GetInstance' static. Also, if
constructor/destructor are empty, then compiler can optimize
them away in release build.

Alex

Alex I'm really sorry for putting bad code in the message. Please bear
with the inconvenience.

class CSingleton
{
public:
    static CSingleton& GetInstance(){ static CSingleton s; return s; }=

private:
    CSingleton(){}
    ~CSingleton(){}

}

VC++ Compiler shows error as the dtor is private and cant' access.

Can't check with VC++ 6.0 but if it rejects to compile it is wrong. It
is valid C++ code. A public destructor would have had been required if
the object of class were being created from a scope outside of the
same class. But here the object is being created from inside a static
member function - the private destructor should be accessible.