Re: Question about singleton class design for tracing

James Kanze <>
25 May 2007 00:33:17 -0700
On May 24, 8:38 pm, Stephen Torri <> wrote:

On Thu, 24 May 2007 02:36:44 -0700, James Kanze wrote:

        static Trace_State& Instance()
            if ( m_instance == 0 )
                    m_instance = new Trace_State();
            return *m_instance;

I'd prefer declare m_instance as static variable in this function, and
of course initiate it :)

This has the disadvantage that the destructor will be called,
potentially leading to order of destruction issues.

Right now I am trying to track down a segfault that occurs in my program.
I find the segfault always has my tracing class as the last point in my
program where control goes through before heading into the STL code. If I
comment out that use of the tracing library then the segfault at that
location disappears. It will occur at the next location using the tracing
library. So I believe the problem is the tracing library design as a
singleton. How can I create a singleton that will not suffer from the
"order of destruction" issue?

As above. Just allocate the object dynamically, and never
delete it.

Note, however, that order of destruction will never be a problem
until you call exit.

I can't look at your original code to see what else might be
wrong. I'm reading news through Google Groups, and they do
something which causes Firefox under Linux to crash in certain
specific cases, at least when using a remote X Server. Looking
at the start of this thread is one of them.

James Kanze (GABI Software)
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