Re: Singleton_pattern and Thread Safety

Leigh Johnston <>
Fri, 10 Dec 2010 20:21:39 +0000
On 10/12/2010 20:06, Ian Collins wrote:

On 12/11/10 02:16 AM, Leigh Johnston wrote:

On 10/12/2010 09:52, James Kanze wrote:

Note that the above still risks order of destruction issues;
it's more common to not destruct the singleton ever, with
something like:

namespace {

Singleton* ourInstance =&Singleton::instance();

if (ourInstance == NULL)
ourInstance = new Singleton;
return *ourInstance;

(This solves both problems at once: initializing the variable
with a call to Singleton::instance and ensuring that the
singleton is never destructed.)

James "Cowboy" Kanze's OO designs includes objects that are never
destructed but leak instead? Interesting. What utter laziness typical of
somebody who probably overuses (abuses) the singleton pattern. Singleton
can be considered harmful (use rarely not routinely).

What James describes is a very common idiom (to avoid order of
destruction issues) and it's certainly one I've often used.

Not considering object destruction when designing *new* classes is bad
practice IMO. Obviously there may be problems when working with
pre-existing designs which were created with a lack of such consideration.


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