Re: single class instance question

Make the constructor private and expose a static factory method, say
"CreateInstance".  Code the factory method to allow only one instance.

--
Steve Johnson

On Sat, Jun 19, 2010 at 6:49 PM, John Smith <[email protected]> wrote:

>
>
> Hi All,
>   Other than through tight source code control, Is there anyway to keep
> multiple instances of a specific class from being created in the same
> program? For example, say I have a class MyClass and somewhere else in the
> code I have an instance of MyClass called MyInstance. Is there anyway to
> keep additional instances of MyClass from being created once MyInstance has
> been created? This is only a potential problem because multiple programmers
> will be working on this particular project.
>
>   I can hear the question now, "Why are multiple instances of the class a
> problem?" The reason is because the class contains functionality that I
> don't want conflicting with another instance of itself. Any ideas on how to
> prevent this?
>
>   I managed to increment an 'instance' counter that increments by 1 each
> time the class constructor is called and inside the constructor I check to
> see if the counter == 1 or not and if not, then I branch to an 'else' block
> and call the class destructor on the second (or subsequent) instance. The
> problem is that I can still call functions in the class through the second
> instance, even after the destructor has been called on it.
>
>
>